1 ACUTE UPPER AIRWAY PRESENTATION IN CATS: NOTHING TO SNEEZE AT

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1 1 ACUTE UPPER AIRWAY PRESENTATION IN CATS: NOTHING TO SNEEZE AT Leah A. Cohn, DVM, PhD, DACVIM (SAIM), University of Missouri, Columbia, Missouri and Eleanor C. Hawkins, DVM, DACVIM (SAIM), North Carolina State University, Raleigh, North Carolina Abstract Upper respiratory infections (URIs) are quite common in cats. Mortality due to common URIs is rare; however, these infections are not trivial. In group settings, and especially when young or unvaccinated cats congregate, URI can spread easily and affect large proportions of the population. In animal shelters especially, these infections can greatly increase costs and decrease ability to place animals in homes. Although a causal link remains unproven, it is entirely possible that acute URI can predispose to later development of chronic rhinosinusitis, a problem in cats that is difficult to manage and usually impossible to cure. In addition, more virulent strains of the common calicivirus infection can and do result in significant mortality as well as morbidity. Key Content A variety of pathogens cause acute URI in cats either alone or in combination. Until and unless a specific diagnosis is obtained, all cats with signs consistent with URI should be treated as if they are contagious. While the clinical signs of URI are similar regardless of causative agent, certain characteristic features of infection may point toward a particular pathogen. Typical feline calicivirus (FCV) infection is a very common cause of URI in cats throughout the world; like many other RNA viruses, FCV is prone to mutation and rapid change. Prevention of feline URI is dependent on both management practices to minimize exposure and vaccination. Causation Feline URI involves multiple risk factors as well as multiple pathogens. 1-4 Pathogens may cause infection alone or in combination. Particularly, secondary bacterial infection may follow primary viral URI. Evidently, viral pathogens are the most common cause of URI in cats. 5,6 Feline calicivirus (FCV) may be more prevalent, 7-9 but feline herpesvirus-1 (FHV-1, or feline rhinotracheitis) often causes more severe clinical disease (with virulent calicivirus infection as an exception) Primary bacterial pathogens involved in feline URI include Bordetella bronchiseptica and Chlamydophila felis. 8,11,12 Secondary bacterial infection with a variety of pathogens can complicate either viral or primary bacterial URI. 13 Prevalence of all of these URI infections is expected to be greater in sheltered populations, in feral cat colonies, or in barn cats than in individually housed cats. 14 Recent data on prevalence of infection in a variety of settings is presented in Table 1. Proceedings of a Symposium Held at the 2008 North American Veterinary Conference and the 2008 Western Veterinary Conference. Copyright 2008 Pfizer Animal Health. All rights reserved. The opinions expressed in the articles in this publication are those of the authors and do not necessarily reflect the official label recommendations and points of view of the company or companies that manufacture and/or market any of the pharmaceutical agents referred to.

2 Table 1 2

3 FCV: Typical and Virulent Systemic Strains 3 Typical FCV infection is a very common cause of URI in cats worldwide. 5,7,15 Like many other RNA viruses, FCV is prone to mutation and rapid change. There are numerous strains of FCV resulting in variable disease manifestations and varied antigenicity. 16 Depending on strain and host factors, infected cats may remain healthy or may develop fever, oral ulcerations, nasal discharge and sneezing, and sometimes lameness. 10,17 The typical oral/respiratory disease is most severe in unvaccinated kittens after maternal antibody has waned (about 10 to 14 weeks). The virus is shed via oral, nasal, and ocular secretions and seems to be spread more easily within a population than in FHV. 5-7 Although more stable in the environment than other causes of feline URI, FCV probably remains infectious for only a week. The greatest viral shedding occurs in the weeks during and after clinical infection, but apparently recovered cats may shed virus persistently for months to years. 17 Recovered carriers may be widespread in localized populations of cats, making it nearly impossible to completely eliminate exposure in large group settings. Prevalence of infection is correlated with the number of cats; pet cats in isolated households have a very low prevalence of infection (<10%), while very high prevalence (up to 90%) can be found in certain shelter or colony settings. 17 Viral systemic strains of feline calicivirus (VS-FCV) result from hypervirulent viral mutants Unlike typical FCV, the virulent strains seem to cause more severe disease in adults (and often in FCV vaccinated cats) than in kittens. VS-FCV results in a disease presentation quite distinct from that of typical FCV infection. Infected cats develop high fevers; swelling (edema) of the face and limbs; alopecia, crusting, and ulceration of the skin (especially the face, ears, and feet); and death. Mortality rates approach 50% even with supportive care. The virus is shed through feces and sloughed skin and hair as well as nasal, oral, and ocular secretions. Mildly affected cats (often kittens) can pass a virulent and potentially fatal form of VS- FCV, so all exposed cats must be considered potentially contagious. The virus itself is readily spread by fomites and may be carried by veterinary personnel to other cats in the facility or even to their own pets at home. Facilities with documented cases of VS-FCV may need to temporarily shut down feline admissions to stop the spread of infection. Fortunately, while ordinary URI due to FCV is common, the virulent form is rare. Feline Herpesvirus-1 Most cats are probably exposed to the single serotype of FHV-1 at some point in their lives. Exposure in susceptible cats can cause moderate to severe respiratory and ocular infection, although vaccinated or older cats may be infected but display minimal clinical signs. The most severe infections typically occur in kittens shortly after maternal antibody wanes (around 9 weeks) and in young, unvaccinated cats. Viral shedding in nasal, oropharyngeal, and ocular discharge is responsible for cat-to-cat and fomitetransmission; aerosol transmission is uncommon, and the virus itself does not persist long in the environment. Two to six days after initial exposure, fever, anorexia, nasal discharge and sneezing, and ocular discharge develop. Many cats hypersalivate, but oral ulceration is uncommon compared with FCV infection. Multiple ocular manifestations are associated with FHV-1 infection. In some cases the causative role is well accepted (e.g.., ulcerative and interstitial keratitis, conjunctivitis), while in others (e.g., corneal sequestrum formation, anterior uveitis, eosinophilic keratitis) a role is likely but not proven definitively Rarely, viral pneumonia and dermatologic symptoms are seen. 24 Mortality rates are low--most cats improve spontaneously in 10 to 20 days. As with all herpesvirus infections, although clinical signs may resolve on their own, the immune system does not eliminate the infection. Instead, viral latency develops. 25 Reactivation of virus can occur at any point later in life, generally in association with stress or immune suppression (e.g., corticosteroid treatment). 26 Prevalence estimates for FHV-1 shedding from nonsymptomatic cats range from 0% to about 8%, depending on methodology and population. Bordetella bronchiseptica This gram-negative coccobacillus is an important cause of respiratory infection in dogs, but it has been given attention as a primary respiratory pathogen in cats only recently. Kittens are no more likely to be

4 4 infected than adult cats but may show more severe clinical signs. Clinical signs following experimental infection of cats included sneezing, oculonasal discharges, submandibular lymphadenopathy, and cough. 27 The organism has also been isolated from naturally infected cats with a range of respiratory signs, including pneumonia. 11,28-31 Spread of infection may be through cat-to-cat contact or via infectious discharges, and shedding can occur for weeks after infection from recovered cats. The organism is also found in healthy cats; it is more likely to cause disease in conditions of stress or overcrowding. The same bacterium can be transmitted between dogs and cats, making it a potential problem in animal shelters where the infection may be more commonly encountered in dogs. 29 Although unusual, B. bronchiseptica may be zoonotic because it can infect immunocompromised humans. 32 Chlamydophila felis This bacteria is predominantly an ocular pathogen. Although it was the first identified cause of feline URI (then known as Chlamydia psittaci), it seems to be a much less prevalent cause of URI than either FHV-1 or FCV in most of the world. 5,8,22,33,34 The organism is still quite important as a cause of conjunctivitis, however. It is labile in the environment and is spread primarily through cat-to-cat contact. From 5 to 10 days after exposure, serous ocular discharge may be seen from one or both eyes. This progresses to bilateral mucopurulent discharge and chemosis, sometimes with sneezing and nasal discharge. 35 Although not a commonly recognized problem, there is evidence that the infection may be transmitted from cats to humans, resulting in human conjunctivitis. 36 Infected cats may continue to shed organisms for months after recovery. Mycoplasma The true role of these fastidious organisms in URI of cats is unknown. Mycoplasma species may be found in the upper airways and oropharynx of healthy dogs and cats and can be detected during lower and upper respiratory infections. 1,37-39 They may simply be secondary pathogens or may play a more important but asyet-undefined primary role in disease. Because they lack a cell wall, they are not cultured with routine methods. The laboratory must be specifically requested to grow the organism, or nucleic acid detection (polymerase chain reaction [PCR]) should be used. Again, because these organisms lack a cell wall, they cannot be killed with beta-lactam type antibiotics (e.g., penicillin derivatives, cephalosporins). Diagnosis Clinical findings associated with URI due to any pathogen are similar (sneezing, nasal/ocular discharge, hyporexia) (Figure 1). Figure 1 Typical appearance of kitten with upper respiratory infection. Unless the kitten is part of a group housing environment (e.g., shelter, cattery), there may be no need to search for a specific causative diagnosis.

5 Despite the similarities, particular manifestations are more likely with one type of infection than another (Table 2). 5 5 Table 2 For example, Chlamydophila is more likely to cause severe conjunctivitis with milder nasal signs, B. bronchiseptica is more likely to cause cough, FCV is likely to result in oral ulcerations (Figure 2), and cats with FHV-1 infection are often more severely lethargic and demonstrate marked nasal signs and possible keratitis.

6 6 Figure 2 Oral ulcerations, like the ones seen on the anterior Portion of this kitten s tongue, are not pathognomonic but are very suggestive of FCV infection. Ocular manifestations of chronic FHV-1 can at times be very characteristic of the condition (Figure 3). Figure 3 Conjunctival hyperemia and multifocal yellowish to tan raised plaques at the superior temporal cornea are typical of eosinophilic keratitis in this FHV-1-infected cat. This, and multiple other ocular abnormalities (acute or chronic), may be consequences of FHV-1 infection. In many situations (especially kittens or cats recently adopted into single-cat households), determining the specific cause is unnecessary. However, confirmation of a specific diagnosis can sometimes be helpful in such settings as catteries or animal shelters. Sometimes, a simple test, such as microscopic evaluation of a conjunctival scraping, may identify inclusions suggestive of Chlamydophila, or characteristic ocular lesion, such as dendritic ulcers, may strongly suggest FHV-1 infection. Often, confirmation of a diagnosis is complicated. For example, although the best way to confirm infection with B. bronchiseptica is via positive culture, it can be isolated from the upper airways of healthy cats. Serologic evidence of exposure to the pathogens associated with URI may mean that the animal actually has the infection or may just be associated with past exposure or even vaccination. For organisms with latency or carrier states, detection of nucleic acids via PCR methods may not imply active infection. Confirmation of VS-FCV depends on isolation of identical viral strains (usually from oropharyngeal swabs or necropsy specimens) from more than one affected cat. No test can differentiate VS-FCV from typical FCV in a single cat.

7 7 Cats may also harbor more than one pathogen simultaneously. These multiple infections may act synergistically to worsen disease manifestation, or one or more pathogens may simply be present without contributing to clinical signs. When bacterial infections are suspected, culture can be used to identify pathogens. For any of the primary pathogens (Bordetella, Chlamydophila, or Mycoplasma), the laboratory should be notified of the clinical suspicion so that appropriate culture media and procedures can be used. Oropharyngeal, tracheal, or deep nasal culture samples should be collected into charcoal Amies transport medium when B. bronchiseptica is suspected. Chlamydophila can be cultured after vigorous conjunctival sampling; swabs should be placed in special media and kept refrigerated before timely laboratory submission. Recently, panels of real-time PCR assays have been offered to detect common causes of URI. Feline URI panels offered by at least one commercial and another university laboratory include assays for FHV-1, FCV, C. felis, M. felis, and B. bronchiseptica. Such panels offer advantages in real-life situations, such as animal shelters where multiple different pathogens may be present. However, as mentioned previously, detection of nucleic acid sequences from a given pathogen cannot be assumed to prove disease causation. Therapy In most cases, cats with URI will recover without specific treatment. Basic nursing care is usually best provided in a home situation, rather than in hospital, both to minimize exposure of other cats to a contagious infection and to minimize stress and likelihood of secondary infection in the affected cat. Hyporexia/anorexia is common but can sometimes be overcome with simple measures, such as feeding foods with strong odors such as fish-based cat food or by warming the food. Rarely, force-feeding is required (e.g., via nasoesophageal tube). Adequate systemic hydration should be maintained (subcutaneous or intravenous fluids are seldom required), and humidification of the environment can help keep respiratory secretions moist. When the infection is isolated to the upper respiratory tract, simple room humidification is adequate. For cats that develop pneumonia, nebulization of plain sterile saline may prove beneficial. If nebulization is used, disinfection or disposal of contaminated equipment is crucial not only to prevent contagion to other cats on which the nebulizer might be used next, but also to prevent worsening of the pneumonia by inoculating pathogens repeatedly into the deep airways. Although some veterinarians have nebulized antimicrobials such as gentamicin, there is no demonstrated benefit of this treatment, especially in viral infection. Also, nebulization of antimicrobials not specifically designed for that purpose can lead to bronchoconstriction. While this is seldom a problem in dogs, the relatively hyperreactive ( twitchy ) airways of cats could put them at greater risk for adverse reaction to nebulized medications. Although ineffective against the most common causes of URI (viral infection), antibiotics are often used empirically. Amoxicillin-clavulanic acid is a good, broad spectrum, empirical choice for control or prophylaxis of secondary infection. 13,40 For treatment of specific bacterial infections, other antibiotics may be indicated. 28,41 Doxycycline has good efficacy against Bordetella, Chlamydophila, and Mycoplasma but may be associated with discoloration of teeth in kittens (including developing feti) and with esophagitis and esophageal stricture. Administration should always be followed with a bolus of water. Other reasonable choices include trimethoprim-sufamethoxazole, fluoroquinolones, and erythromycin-type compounds, such as azithromycin and clarithromycin. 41,42 Treatment of cats with azithromycin for C. felis resulted in rapid clinical improvement, but this treatment was unable to eradicate carriage of the pathogen. 43 Doxycycline, however, resulted in both clinical improvement and apparent cure. 40 In cats with C. felis conjunctivitis, ophthalmic chloramphenicol or tetracycline ointments should also be applied. These ointments may be useful in cats with corneal ulcers due to FHV. Antiviral drugs are not generally used to treat URI manifestations of disease but are often used to treat ocular manifestations of the infections. Acyclovir, used to treat herpes infections in humans, does not seem to have good efficacy against FHV-1. 20,44 When administered systemically, acyclovir and related antiviral

8 8 drugs are potentially very toxic in cats. 45,46 The one systemic antiviral medication in common use is L- lysine. 47,48 Available as a nutriceutical, L-lysine (500 mg/po BID) is believed to interfere with herpesvirus replication. A recent study of enzootic URI in cats fed a lysine-supplemented diet was unable to demonstrate improvement in clinical manifestations of disease. 49 Because lysine administration can lead to decreased arginine and because cats are sensitive to arginine deficiency, long-term lysine administration should be undertaken only with caution. In cats with corneal ulcers resulting form FHV, topical antiviral drugs, such as trifluridine, idoxuridine, or adenine arabinoside, can also be used. 50 Prevention Prevention of feline URI is dependent on both management practices to minimize exposure and vaccination. Minimization of crowding and stress, cleanliness, and routine disinfection are all crucial when cats are housed in groups, such as in catteries or shelters. A thorough discussion of shelter design and management is beyond the scope of this discussion; however, the Web site of the University of California Davis Koret Shelter Medicine Program ( can provide further detail on this topic. As an unenveloped virus, FCV is resistant to many routine disinfectants but is susceptible to a 5% bleach solution diluted 1:32 (1/2 cup per gallon of water) or potassium peroxymonosulfate. It should be noted that no disinfectants work in the presence of organic debris, so basic cleaning must precede disinfection. Vaccinations are available for FCV, virulent FCV, FHV-1, Chlamydophila, and B. bronchiseptica in cats. For individual pet cats, the 2006 American Association of Feline Practitioners Feline Vaccine Advisory Panel recommends that vaccination against both FCV and FHV-1 should be considered core vaccines. 51 However, it is important to understand that vaccination does not prevent infection or development of a carrier state, but rather minimizes disease severity. 52,53 In addition, there may be resistant strains of typical (and of course, virulent) FCV. Both FCV and FHV-1 vaccines can be found as modified-live (MLV) and killed vaccine for parenteral injection or as MLV for intranasal administration. Occasionally, respiratory signs follow intranasal vaccination. Likewise, cats may develop mild signs of URI if they groom MLV from the fur following vaccination. Killed vaccines may be preferred for pregnant queens and cats with concurrent retroviral infection, but otherwise use of MLV is standard. After initial vaccination and booster vaccination at 1 year, immunity is likely to last at least 3 years, so more frequent revaccination is unnecessary Serologic testing can be used as a surrogate marker of protection after vaccination for FHV and FCV. 58 Both Chlamydophila and Bordetella vaccines are considered noncore and are generally not suggested for use in pet cats. 51 Vaccination in shelters has a different set of considerations from individual pet vaccination. Unless records are available to prove otherwise, cats are assumed to be unvaccinated and are vaccinated immediately upon shelter entry. Because intranasal vaccination can cause mild clinical signs, this can cause confusion in shelters deciding which cats should be isolated or even culled. However, even injectable MLV vaccines occasionally induce clinical signs (e.g., after grooming the area of vaccine administration), intranasal vaccines may offer more rapid protection than injectable vaccines, and at least one paper suggests that intranasal vaccination in addition to injectable vaccination for FCV/FHV-1 offers increased protection. 59 Although also important for pet cats, the role of vaccination in minimizing viral shedding is particularly relevant in shelters. In addition to reducing clinical signs, in at least some cases vaccination reduces viral shedding. 60 Vaccination against Chlamydophila is reserved for shelters with a demonstrated problem with the infection. Even then, vaccination does not prevent infection or shedding but only reduces disease severity. Because there is some risk for zoonotic transmission, some shelters prefer to cull infected cats. If this is the case, vaccination could interfere with recognition of infection. The importance of Bordetella in causing URI in sheltered cats is unclear, but the infection can be transmitted between species (dogs and cats). 8,28,29 In shelters with a demonstrable problem with Bordetella infection in dogs or cats, intranasal vaccination of cats may be warranted.

9 9 Recently, a vaccination for virulent systemic FCV has become available (CaliciVax, Fort Dodge Animal Health). This killed virus vaccine incorporates one of several strains of FCV known to cause severe systemic disease. Generally, hypervirulent strains of FCV have arisen from new genetic mutations in each group of cats infected. 19 Although the new vaccine demonstrated protection from challenge with the same virulent strain used in its development, to our knowledge challenge has not be attempted (and therefore protection has not been demonstrated) with any other virulent strain. Images courtesy of Dr. Elizabeth Giuliano, DACVO. References 1. Johnson LR, Foley JE, De Cock HE, et al. Assessment of infectious organisms associated with chronic rhinosinusitis in cats. J Am Vet Med Assoc. 2005;227: Demko JL, Cohn LA. Chronic nasal discharge in cats: 75 cases ( ). J Am Vet Med Assoc. 2007;230: Henderson SM, Bradley K, Day MJ, et al. Investigation of nasal disease in the cat--a retrospective study of 77 cases. J Feline Med Surg. 2004;6: Hurley KE, Pesavento PA, Pedersen NC, et al. An outbreak of virulent systemic feline calicivirus disease. J Am Vet Med Assoc. 2004;224: Bannasch MJ, Foley JE. Epidemiologic evaluation of multiple respiratory pathogens in cats in animal shelters. J Fel Med Surg. 2005;7: Coyne KP, Dawson S, Radford AD, et al. Long-term analysis of feline calicivirus prevalence and viral shedding patterns in naturally infected colonies of domestic cats. Vet Micro. 2006;118: Binns SH, Dawson S, Speakman AJ, et al. A study of feline upper respiratory tract disease with reference to prevalence and risk factors for infection with feline calicivirus and feline herpesvirus J Feline Med Surg. 2000;2: Helps CR, Lait P, Damhuis A, et al. Factors associated with upper respiratory tract disease caused by feline herpesvirus, feline calicivirus, Chlamydophila felis and Bordetella bronchiseptica in cats: experience from 218 European catteries. Vet Rec. 2005;156: Mochizuki M, Kawakami K, Hashimoto M, et al. Recent epidemiological status of feline upper respiratory infections in Japan. J Vet Med Sci. 2000;62: Hurley KF, Sykes JE. Update on feline calicivirus: new trends. Vet Clin North Am Small Anim Pract. 2003;33: Hoskins JD, Williams J, Roy AF, et al. Isolation and characterization of Bordetella bronchiseptica from cats in southern Louisiana. Vet Immunol Immunopathol. 1998;65: Ramsey DT. Feline chlamydia and calicivirus infections. Vet Clin North Am Small Anim Pract. 2000;30: Dossin O, Gruet P, Thomas E. Comparative field evaluation of marbofloxacin tablets in the treatment of feline upper respiratory infections. J Small Anim Pract. 1998;39: Cave TA, Thompson H, Reid SW, et al. Kitten mortality in the United Kingdom: a retrospective analysis of 274 histopathological examinations (1986 to 2000). Vet Rec. 2002;151: Cai Y, Fukushi H, Koyasu S, et al. An etiological investigation of domestic cats with conjunctivitis and upper respiratory tract disease in Japan. J Vet Med Sci. 2002;64: Hoover EA, Kahn DE. Experimentally induced feline calicivirus infection: clinical signs and lesions. J Am Vet Med Assoc. 1975;166: Radford AD, Coyne KP, Dawson S, et al. Feline calicivirus. Vet Res. 2007;38: Coyne KP, Jones BR, Kipar A, et al. Lethal outbreak of disease associated with feline calicivirus infection in cats. Vet Rec. 2006;158: Ossiboff RJ, Sheh A, Shotton J, et al. Feline caliciviruses (FCVs) isolated from cats with virulent systemic disease possess in vitro phenotypes distinct from those of other FCV isolates. J Gen Virol. 2007;88:

10 Williams DL, Fitzmaurice T, Lay L, et al. Efficacy of antiviral agents in feline herpetic keratitis: results of an in vitro study. Curr Eye Res. 2004;29: Maggs DJ. Update on pathogenesis, diagnosis, and treatment of feline herpesvirus type 1. Clin Tech Small Anim Pract. 2005;20: Rampazzo A, Appino S, Pregel P, et al. Prevalence of Chlamydophila felis and feline herpesvirus 1 in cats with conjunctivitis in northern Italy. J Vet Intern Med. 2003;17: Nasisse MP. Feline herpesvirus ocular disease. Vet Clin North Am Small Anim Pract. 1990;20: Gutzwiller ME, Brachelente C, Taglinger K, et al. Feline herpes dermatitis treated with interferon omega. Vet Derm. 2007;18: Gaskell RM, Dennis PE, Goddard LE, et al. Isolation of felid herpesvirus I from the trigeminal ganglia of latently infected cats. J Gen Virol. 1985;66: Gaskell R, Povey R. Re-excretion of feline viral rhinotracheitis virus following corticosteroid treatment. Vet Rec. 1973;93: Williams J, Laris R, Gray AW, et al. Studies of the efficacy of a novel intranasal vaccine against feline bordetellosis. Vet Rec. 2002;150: Foley JE, Rand C, Bannasch MJ, et al. Molecular epidemiology of feline bordetellosis in two animal shelters in California, USA. Prev Vet Med. 2002;54: Dawson S, Jones D, McCracken CM, et al. Bordetella bronchiseptica infection in cats following contact with infected dogs. Vet Rec. 2000;146: Binns SH, Dawson S, Speakman AJ, et al. Prevalence and risk factors for feline Bordetella bronchiseptica infection Vet Rec : Welsh RD. Bordetella bronchiseptica infections in cats. J Am Anim Hosp Assoc. 1996;32: Berkowitz DM, Bechara RI, Wolfenden LL. An unusual cause of cough and dyspnea in an immunocompromised patient. Chest : Helps C, Reeves N, Egan K, et al. Detection of Chlamydophila felis and feline herpesvirus by multiplex real-time PCR analysis. J Clin Microbiol. 2003;41: Sykes JE, Allen JL, Studdert VP, et al. Detection of feline calicivirus, feline herpesvirus 1 and Chlamydia psittaci mucosal swabs by multiplex RT-PCR/PCR. Vet Microbiol. 2001;81: Sykes JE. Feline chlamydiosis. Clin Tech Small Anim Pract. 2005;20: Hartley JC, Stevenson S, Robinson AJ, et al. Conjunctivitis due to Chlamydophila felis (Chlamydia psittaci feline pneumonitis agent) acquired from a cat: case report with molecular characterization of isolates from the patient and cat. J Infect. 2001;43: Johnson LR, Drazenovich NL, Foley JE. A comparison of routine culture with polymerase chain reaction technology for the detection of Mycoplasma species in feline nasal samples. J Vet Diag Invest. 2004;16: Chandler JC, Lappin MR. Mycoplasmal respiratory infections in small animals: 17 cases ( ). J Am Anim Hosp Assoc. 2002;38: Foster SF, Barrs VR, Martin P, et al. Pneumonia associated with Mycoplasma spp in three cats. Aust Vet J. 1998;76: Sykes JE, Studdert VP, Browning GF. Comparison of the polymerase chain reaction and culture for the detection of feline Chlamydia psittaci in untreated and doxycycline-treated experimentally infected cats. J Vet Intern Med. 1999;13: Speakman AJ, Binns SH, Dawson S, et al. Antimicrobial Susceptibility of Bordetella bronchiseptica isolates from cats and a comparison of the agar dilution and E-test methods. Vet Microbiol. 1997;54: Carbone M, Pennisi MG, Masucci M, et al. Activity and postantibiotic effect of marbofloxacin, enrofloxacin, difloxacin and ciprofloxacin against feline Bordetella bronchiseptica isolates. Vet Microbiol. 2001;81: Owen WM, Sturgess CP, Harbour DA, et al. Efficacy of azithromycin for the treatment of feline chlamydophilosis. J Feline Med Surg. 2003;5: Williams DL, Robinson JC, Lay E, et al. Efficacy of topical aciclovir for the treatment of feline herpetic keratitis: results of a prospective clinical trial and data from in vitro investigations. Vet Rec. 2005;157: Nasisse MP, Dorman DC, Jamison KC, et al. Effects of valacyclovir in cats infected with feline herpesvirus 1. Am J Vet Res. 1997;58:

11 Owens JG, Nasisse MP, Tadepalli SM, et al. Pharmacokinetics of acyclovir in the cat. J Vet Pharmacol Ther. 1996;19: Maggs DJ, Nasisse MP, Kass PH. Efficacy of oral supplementation with L-lysine in cats latently infected with feline herpesvirus. Am J Vet Res. 2003;64: Maggs DJ, Collins BK, Thorne JG, et al. Effects of L-lysine and L-arginine on in vitro replication of feline herpesvirus type-1. Am J Vet Res. 2000;61: Maggs DJ, Sykes JE, Clarke HE, et al. Effects of dietary lysine supplementation in cats with enzootic upper respiratory disease. J Feline Med Surg. 2007;9: Maggs DJ, Clarke HE. In vitro efficacy of ganciclovir, cidofovir, penciclovir, foscarnet, idoxuridine, and acyclovir against feline herpesvirus type-1. Am J Vet Res. 2004;65: Richards JR, Elston TH, Ford RB, et al. The 2006 American Association of Feline Practitioners Feline Vaccine Advisory Panel Report. J Am Vet Med Assoc. 2006;229: Orr CM, Gaskell CJ, Gaskell RM. Interaction of a combined feline viral rhinotracheitis-feline calicivirus vaccine and the FVR carrier state. Vet Rec. 1978;103: Pedersen NC, Hawkins KF. Mechanisms for persistence of acute and chronic feline calicivirus infections in the face of vaccination. Vet Microbiol. 1995;47: Schultz RD. Duration of immunity for canine and feline vaccines: a review. Vet Microbiol. 2006;117: Mouzin DE, Lorenzen MJ, Haworth JD, et al. Duration of serologic response to three viral antigens in cats. J Am Vet Med Assoc. 2004;224: Gore TC, Lakshmanan N, Williams JR, et al. Three-year duration of immunity in cats following vaccination against feline rhinotracheitis virus, feline calicivirus, and feline panleukopenia virus. Vet Ther. 2006;7: Scott FW, Geissinger CM. Long-term immunity in cats vaccinated with an inactivated trivalent vaccine. Am J Vet Res. 1999;60: Lappin MR, Andrews J, Simpson D, et al. Use of serologic tests to predict resistance to feline herpesvirus 1, feline calicivirus, and feline parvovirus infection in cats. J Am Vet Med Assoc. 2002;220: Edinboro CH, Janowitz LK, Guptill-Yoran L, et al. A clinical of intranasal and subcutaneous vaccines to prevent upper respiratory infection in cats at an animal shelter. Feline Pract. 1999;27: Lappin MR, Lappin MR, Sebring RW, et al. Effects of a single dose of an intranasal feline herpesvirus 1, calicivirus, and panleukopenia vaccine on clinical signs and virus shedding after challenge with virulent feline herpesvirus 1. J Feline Med Surg. 2006;8: Coutts AJ, Dawson S, Willoughby K, et al. Isolation of feline respiratory viruses from clinically healthy cats at UK cat shows. Vet Rec. 1994;135: Sykes JE, Anderson GA, Studdert VP, et al. Prevalence of feline Chlamydia psittaci and feline herpesvirus 1 in cats with upper respiratory tract disease. J Vet Intern Med. 1999;13: Gaskell R, Dawson S, Radford A, et al. Feline herpesvirus. Vet Res. 2007;38:

12 1 THE CONUNDRUM OF THE CONTAGIOUS CANINE COUGH Eleanor C. Hawkins, DVM, Diplomate, ACVIM (SAIM), North Carolina State University, Raleigh, North Carolina, and Leah A. Cohn, DVM, PhD, Diplomate, ACVIM (SAIM), University of Missouri, Columbia, Missouri Abstract You are presented with a dog with acute cough. Is it kennel cough? Influenza? What should you advise your client? What should you do to protect your other patients? This article discusses the diagnosis, treatment, and prevention of canine infectious cough, with particular emphasis on Bordetella and influenza infections. Key Content Treat all dogs that present with signs of acute tracheobronchitis as if they are infectious. For both bordetellosis and influenza without pneumonia, the primary treatment is supportive care and time. For bordetellosis and influenza pneumonia, appropriate antibiotic therapy is indicated in addition to intense supportive care. Be vigilant regarding infectious disease protocols in your hospital in order to avoid contributing to the spread of any infectious disease. There are many infectious causes of acute cough in dogs and include viruses (e.g., canine influenza virus, distemper virus, parainfluenza virus, adenovirus 2), bacteria (e.g., Bordetella bronchiseptica, Mycoplasma species, Streptococcus equi subspecies zooepidemicus), protozoa, mycoses, and parasites (Table 1). Proceedings of a Symposium Held at the 2008 North American Veterinary Conference and the 2008 Western Veterinary Conference. Copyright 2008 Pfizer Animal Health. All rights reserved. The opinions expressed in the articles in this publication are those of the authors and do not necessarily reflect the official label recommendations and points of view of the company or companies that manufacture and/or market any of the pharmaceutical agents referred to.

13 2 Table 1 Bordetella bronchiseptica and the respiratory viruses are particularly contagious organisms, and infection in a dog presented to your hospital has important implications for the patient and client, as well as for other patients in your hospital and other dogs that have come in contact with the coughing dog. Infections with respiratory viruses, other than distemper and influenza, are generally mild and short-lived if uncomplicated by co-infections. Vaccination against infection with distemper is wide-spread and generally effective. Therefore, this discussion will focus on infections with Bordetella and influenza virus. Presentation A recent history of exposure to other dogs with cough or to group housing situations is supportive of a diagnosis of infection with either Bordetella or influenza because both are highly contagious. 1-4 Influenza tends to have a shorter incubation period (usually less than 1 week, compared with up to 2 weeks for Bordetella), and because most dogs are naïve to influenza antigens, spread of disease in an exposed population of dogs may be more extensive. 1-4 Most dogs diagnosed with influenza infections are from dense, group housing situations. 1-3 Cough is often the presenting sign of dogs with either Bordetella or influenza infections. 1-4 Either infection can result in a loud, harsh cough that is readily induced by tracheal palpation (more

14 3 typical of tracheobronchitis) or a soft, moist cough (more typical of pneumonia). Bordetella most often causes a loud, harsh cough, while influenza most often results in a soft, moist cough. 2 Nasal discharge is more common in dogs with influenza than in those with Bordetella. 1-4 Dogs with influenza are often sicker and more lethargic than dogs with Bordetella. 1-3 Either infection can result in signs of overt pneumonia, such as soft cough, tachypnea, increased respiratory efforts, auscultable crackles, or fever. This more severe form of influenza has been identified most often in stressed patients, such as dogs from race tracks or animal shelters. 1-3 A peracute, hemorrhagic pneumonia due to influenza has been reported in race track greyhounds. 1,3 Bordetella can result in pneumonia, particularly in puppies. A recent study found that of 65 puppies with community-acquired infectious pneumonia, 49% had infection with Bordetella. 5 Following are two clinical vignettes of dogs with presentations that are consistent with either Bordetella or influenza infection. A 5-year-old, spayed female Labrador retriever is presented to you with acute, harsh cough. The dog had been boarding at a small facility within your hospital for a weekend and was picked up 2 weeks ago. The coughing began 3 days ago, and the dog developed a bilateral mucopurulent nasal discharge yesterday. The cough is worse with exercise and following drinking. According to the owner, the dog is otherwise healthy with normal appetite and activity, no vomiting or diarrhea, no coughing or sneezing, and no polyuria or polydipsia. The dog primarily stays indoors, but spends some time in a fenced residential back yard. There are no other dogs in the household. The dog was vaccinated against distemper, adenovirus, parainfluenza virus, parvovirus, leptospirosis, and rabies 16 months ago. She received a subcutaneous Bordetella vaccine upon entry into the boarding facility. On physical examination, the dog s attitude is normal and she is in good body condition. Temperature, pulse, and respiration are all within normal limits. The dog has dried mucoid material below both nostrils. A loud, honking cough can be induced on tracheal palpation. The lungs and heart are normal on auscultation. The remainder of the physical examination is unremarkable. Prioritization of differential diagnoses: The loud, honking cough is most typical of tracheobronchitis, rather than pneumonia or pulmonary edema. Bordetella often causes such a harsh cough, while influenza usually causes a soft cough. However, the nasal discharge is more typical of influenza. Presuming that the infection was acquired during boarding, the incubation period is more consistent with bordetellosis than with influenza. The apparent lack of signs in

15 4 other dogs that had been boarding is inconsistent with the more novel agent, influenza. Although the dog had been vaccinated against Bordetella, the vaccine only minimizes clinical signs and does not prevent infection. Further, the dog was vaccinated on the day of boarding, which does not allow time for a maximal immune response. Bordetella is the most likely differential diagnosis in this patient; however, influenza has only recently been recognized, and the range of presenting signs has not been fully determined. A 3-month-old, male Yorkshire terrier is presented to you for decreased appetite, decreased activity, and soft cough of 3-days duration. The owner reports no other clinical signs. The pup lives indoors in an apartment but is taken daily to a local park to exercise and play with other puppies. He has completed his vaccination series for distemper, adenovirus, parainfluenza, adenovirus, and parvovirus and has received his first rabies vaccine. On physical examination, the puppy is quiet. Temperature and pulse are normal, but respiration is increased at 40 breaths/minute. He has mildly stenotic nares, and inspiration requires moderate effort. No cough can be induced on tracheal palpation. A bilateral serous nasal discharge is present. Auscultation is difficult because of referred upper airway sounds. The examination is otherwise unremarkable. Prioritization of differential diagnoses: Although the emphasis of this discussion is on bordetellosis and influenza, other differential diagnoses that should be considered include distemper infection and aspiration pneumonia. The time frame, character of cough, and exposure history are all compatible with a diagnosis of influenza. The cough is not typical of tracheobronchitis, but rather pneumonia. However, Bordetella infection has been associated with pneumonia, particularly in puppies. Both infections should be considered as possibilities. Diagnostic Evaluation Systemic screening tests (CBC, serum biochemical panel, urinalysis) and thoracic radiographs are indicated in all patients with signs suggestive of pneumonia. Even in patients without overt signs of pneumonia on physical examination, a CBC and thoracic radiographs will increase the sensitivity of identifying the presence of pneumonia (Figure 1).

16 5 Thoracic radiographs showing abnormalities characteristic of bacterial bronchopneumonia or aspiration pneumonia. An alveolar pattern is identified by the presence of air bronchograms. The pattern is most severe in the cranial (gravity dependent) lung lobes. A. Lateral view. B. Ventrodorsal view. It should be noted that neither a normal CBC nor body temperature can be used to rule out pneumonia because only half of patients with pneumonia have fever or leukocytosis on presentation. If thoracic radiographs confirm the presence of bronchopneumonia and the patient is sufficiently stable, then a tracheal wash is performed before antibiotic therapy is initiated (Figure 2).

17 6 Figure 2 Performing a transtracheal wash in a dog with signs of bronchopneumonia. Bacterial culture can confirm a diagnosis of bordetellosis (Figure 3). Figure 3 Cytology of a transtracheal wash shows intracellular rods. Neutrophilic inflammation was also present. Aerobic culture resulted in growth of Bordetella bronchiseptica

18 7 Most important, antibiotic sensitivity information for Bordetella organisms or for secondary bacteria in cases with influenza can be invaluable in guiding the treatment of these potentially fatal infections. Patients with mild clinical signs due to either Bordetella or influenza are unlikely to benefit directly from a definitive diagnosis because these infections are usually self-limiting. However, a definitive diagnosis may be useful for treatment of patients with more severe clinical signs and for developing recommendations for monitoring previously exposed dogs or the duration of isolation of the infected dog. Bordetella bronchiseptica A practical method for obtaining a definitive diagnosis of Bordetella infection is by tracheal wash cytology and culture. Cytology is expected to show septic, neutrophilic inflammation with small, Gram-negative rods. Organism identification is confirmed through routine bacterial culture. Polymerase chain reaction (PCR) testing for multiple respiratory pathogens, including B. bronchiseptica, is available commercially and through certain university-based laboratories. Deep pharyngeal swabs are suggested for testing, although Bordetella can be found in the pharynx of some healthy dogs by culture of pharyngeal swabs, so tracheal wash specimens may provide more specific results. Sensitivity and specificity of PCR testing for a clinical population have not been established, nor has the effect of prior antibiotic treatment. Tracheal wash culture for the diagnosis of bordetellosis is preferred over testing by PCR because important antibiotic sensitivity data are obtained concurrently. In outbreaks, it may be prudent to obtain both bacterial cultures and a PCR panel because the panel has the potential also to identify nonbacterial pathogens. Examples of other pathogens for which PCR testing is available include canine influenza virus, canine distemper virus, canine adenovirus type 2, canine parainfluenza virus type 3, canine herpesvirus, and canine respiratory coronavirus. Canine Influenza Serology, enzyme-linked immunosorbent assay (ELISA) for antigen detection, virus isolation, and PCR can be used to confirm a diagnosis of influenza, but each has its strengths and weaknesses. Advantages of serology are that blood is easy to collect, and infection can be detected even after viral shedding has ceased. The main weakness of serology is that confirmation must be delayed pending collection of convalescent serum to confirm rising antibody titers. More timely results are possible with antigen detection methods and PCR. Preliminary data using nasal swabs for specimens indicate that PCR is much more sensitive in virus detection than is antigen detection by ELISA or virus isolation. 6 Other specimens that can be submitted for virus isolation or PCR are pharyngeal swabs, tracheal wash fluid, or lung tissue. Any test for viral detection can yield false-negative results because of the relatively short period of shedding after the development of signs in most patients. For best results, samples should be collected from febrile dogs very early in the course of disease. Treatment Mild Disease Mild disease due to either Bordetella or influenza infection is generally self-limiting. No specific treatment is clearly beneficial. As a bacteria, Bordetella should theoretically be responsive to antibiotic therapy. While antibiotics may shorten the duration of clinical signs, no antibiotic protocol is known to eliminate the organism. Further, some antibiotics may not reach the site of

19 8 infection in therapeutic concentrations. Bordetella organisms can be found on the surface of the epithelial cells, and to be effective against these organisms antibiotics would need to reach adequate concentrations in the epithelial lining fluid. However, other factors may influence the ability of antibiotics to reach the airway lumen, including inflammation and the potential for some drugs to be delivered to the site of infection in inflammatory cells. Sensitivity of B. bronchiseptica to antibiotics is not predictable, and published reports have shown an evolution in sensitivity over time. In reports within the past 10 years, 7,8 most isolates were reported to be sensitive to doxycycline, chloramphenicol, enrofloxacin, and amoxicillin/clavulanate. Fewer isolates were sensitive to trimethoprim-sulfa, and much resistance was found to first-generation cephalosporins and ampicillin. Although amoxicillin/clavulanate is not believed to reach high concentrations in the epithelial lining fluid of healthy dogs, it has a high margin of safety and is a reasonable option for dogs with non lifethreatening infection. It should be administered three times daily at the high end of the dose range to maximize the time above minimum inhibitory concentrations. Such frequent dosing is inconvenient for many owners. Fluoroquinolones reach high concentrations in the epithelial lining fluid but should generally be reserved for more significant infections. Chloramphenicol reaches adequate airway concentrations and is a rational choice for puppies where fluoroquinolones and tetracyclines may be relatively contraindicated. Doxycycline reaches reasonable airway concentrations in humans but is more highly protein-bound in dogs and may not penetrate into the epithelial lining fluid as readily. 9 It also has the disadvantage of dental staining in puppies. Azithromycin can achieve high airway concentrations, is convenient for owners, and is used to treat B. pertussis in humans, but sensitivity to B. bronchiseptica has not been reported. In addition, the spectrum of azithromycin is quite narrow. Another strategy to reach high airway concentrations is by nebulization of antibiotics. Some veterinarians report success in controlling signs and kennel outbreaks with nebulized gentamicin, 10 but no controlled studies have been published. As with oral antibiotic therapy, it has been shown that nebulized antibiotic therapy does not eliminate Bordetella from the airways of infected dogs. 11 Oseltamivir phosphate is the specific treatment for influenza in people. To be effective, the drug must be given within 12 to 48 hours of the onset of signs, and the major benefit is a decrease in the median duration until improvement of signs by just over 1 day. In dogs, no controlled efficacy trials are available and to our knowledge dose and toxicity studies have not been done, although the drug has been used by individuals to treat dogs with upper respiratory tract signs and parvovirus infection. It is unlikely that a sufficiently early diagnosis will be possible in most cases for this drug to have practical benefit. Other considerations that limit the potential utility of the antiviral drug in dogs are the potential for creating viral resistance and the appropriateness of using a potentially scarce human resource, particularly in the absence of data supporting any benefit for dogs with mild clinical signs. Effectiveness of nonspecific treatments for mild, infectious cough has not been extensively explored. One limited field study of dogs with infectious tracheobronchitis found no benefit to the administration of steroids. 12 Cough suppressants are often prescribed. Potential benefits are the reduction of secondary inflammation caused by persistent coughing and allowing rest for the patient and owners. A potential disadvantage is reducing airway clearance in a patient who may have disrupted ciliary function. In the authors experience, cough is best controlled by minimizing stimuli that induce cough, such as excitement or pressure from a collar, combined with judicious use of narcotic cough suppressants on an as-needed basis. Cough suppressants are always contraindicated in animals with pneumonia.

20 9 Severe Disease: Pneumonia Although primary viral pneumonia due to influenza does occur on occasions, most dogs with pneumonia related to influenza have secondary bacterial infections. As discussed with mild disease, specific antiviral drugs are not known to be effective. Therefore, dogs with severe pneumonia due to either bordetellosis or influenza are treated according to general recommendations for bacterial bronchopneumonia. Initially, antibiotics should be broadspectrum. Modification to treatment is then based on results of cultures of airway specimens and response to treatment. Reported sensitivity results for Bordetella isolates were discussed above, but dogs with severe pneumonia due to Bordetella may occasionally have infection complicated by other bacteria. A variety of bacteria have been isolated from dogs with influenza, including Streptococcus equi subspecies zooepidemicus and gram-negative organisms that are resistant to commonly prescribed antibiotics. Antibiotics to consider for initial treatment of severe pneumonia include the combination of ampicillin with sulbactam and either a fluoroquinolone or an aminoglycoside, or meropenem. Protecting Other Dogs Bordetella may persist in the airways of dogs for up to 3 months, 13 although clinically dogs do not seem to be particularly infective for this prolonged period. This early study, based on experimentally induced infection, found that bacterial counts were related to clinical signs, with bacterial numbers decreasing along with signs. 13 Resolution of coughing may also reduce the physical spread of organisms. Vaccination against bordetellosis probably decreases the duration of shedding of organisms if administered before exposure Influenza may be shed for as long as 10 days in infected dogs and can be shed by asymptomatic dogs. However, by the time of presentation it is often difficult to isolate virus from pharyngeal swabs. In a hospital, shelter, or other group housing environment, it is critical to immediately isolate any acutely coughing dog and to disinfect all areas of contact. Both Bordetella and influenza are killed by routine disinfectants. It is important to note that disinfectants cannot work in the presence of organic debris; therefore, the environment must be cleaned thoroughly before it is disinfected. Dogs with either disease may shed organisms before the onset of classic clinical signs. Therefore, it is essential that routine infection control procedures be consistently followed for every animal (Figure 4). Washing hands between every patient is an essential component of infection control.

21 10 Examples of common failures in hospital infection control are listed in Table 2. Table 2 The AVMA has a useful Web site entitled Recommendations for Managers and Workers of Kennel Facilities ( Prevention There is no vaccine available for canine influenza, and early studies of the equine product have not been promising. 17 Vaccines are available for Bordetella, but are effective only in decreasing clinical signs and duration of shedding. Therefore, the most important means of preventing infection with either of these agents is to avoid exposure. In addition, otherwise-healthy animals are less likely to develop severe disease manifestations if they are exposed to these pathogens. Vaccines that are currently available for Bordetella in dogs include modified live intranasal products and a subcutaneously administered antigen extract product. Comparison of vaccine efficacy is difficult for several reasons. First, protection with respect to Bordetella vaccines means decreased severity and duration of clinical signs; these important endpoints for the client introduce subjectivity into scientific studies. Second, because host, environmental, and organism (strain) factors play important roles in severity of clinical signs, vaccination efficacy will probably be different under different experimental situations. 18,19 Third, manufacturers continually aim to improve their product, and the products reported in studies published in refereed journals are not always the currently available commercial products. Lastly, vaccine efficacy studies are extremely difficult and expensive to perform. The different routes of administration of vaccine stimulate the immune system in different ways. Local immunity (e.g., secretory IgA) would be expected to have more robust stimulation with intranasal administration; systemic immunity (e.g., IgG) would be expected to have more robust stimulation with subcutaneous administration. Limitations of published studies are such that it is too early to conclude that sequential administration of both types of vaccine is necessary in a clinical setting. Onset of protection may be an important consideration in shelters or for controlling outbreaks. One study showed that protection was provided by intranasal vaccination at 72 hours (3 days) postvaccination, but not at 24 or 48 hours. 18 Specific serum IgG concentrations in seropositive

22 11 dogs (dogs previously vaccinated or exposed to natural infection) that were vaccinated with a subcutaneous product began increasing between 4 and 5 days after vaccination. 19 Based on the 2006 AAHA canine vaccine guidelines, either type of vaccine should be administered to dogs with expected exposure at least 1 week in advance of exposure. Yearly boosters are given thereafter. Boosters should be given every 6 months if the dog is going to be boarded or will be in some other situation in which exposure is likely greater than 6 months after receiving the previous vaccination. This is outside of the manufacturers recommendations. Puppies at risk for exposure are vaccinated according to manufacturers recommendations (generally 2 subcutaneous vaccines or 1 intranasal vaccine is administered, depending on the age at first vaccination).

23 12 References 1. Crawford PC, Dubovi EJ, Castleman WL, et al. Transmission of equine influenza virus to dogs. Science. 2005; 310: Crawford C. Canine influenza virus (canine flu), University of Florida College of Veterinary Medicine Veterinary Advisory, Yoon K.J, Cooper VL, Schwartz KJ, et al. Influenza virus in racing greyhounds. Emerg Infect Dis. 2005;11: Thrusfield MV, Aitken CGG, Muirhead RH. A field investigation of kennel cough: incubation period and clinical signs. J Small Anim Pract. 1991;32: Radhakrishnan A, Drobatz KJ, Culp WT, King LG. Community-acquired infectious pneumonia in puppies: 65 cases ( ). J Am Vet Med Assoc. 2007;230: Spindel ME, LunnKF, Dillion S, Landolt GA. Detection and quantification of canine influenza virus by one-step real-time reverse transcription PCR (Abstract). J Vet Intern Med. 2007;21: Speakman AJ, Dawson S, Corkill JE, Binns SH, Hart CA, Gaskell RM. Antibiotic susceptibility of canine Bordetella bronchiseptica isolates. Vet Microbiol. 2000;71: Foley JE, Rand C, Bannasch MJ, Norris CR, Milan J. Molecular epidemiology of feline bordetellosis in two animal shelters in California, USA. Prev Vet Med. 54: , Bidgood TL, Papich MG. Comparison of plasma and interstitial fluid concentrations of doxycycline and meropenem following constant rate intravenous infusion in dogs. Am J Vet Res. 2003;64: Miller CJM, McKiernan BC, Hauser C, Fettman MJ. Gentamicin aerosolization for the treatment of infectious tracheobronchitis (abstract). Proc Am Coll Vet Intern Med; Bemis DA, Appel MJG. Aerosol, parenteral, and oral antibiotic treatment of Bordetella bronchiseptica infections in dogs. J Am Vet Med Assoc. 1977;170: Thrusfield MV, Aitken CGG, Muirhead RH. A field investigation of kennel cough: efficacy of different treatments. J Small Anim Pract. 1991;32: Bemis DA, Greisen HA, Appel MJG. Pathogenesis of canine bordetellosis. J Infect Dis. 1977;135: Jacobs AAC, Theelen RPH, Jaspers R, Horspool LJI, Sutton D, Bergman JGHE, et al. Protection of dogs for 13 months against Bordetella bronchiseptica and canine parainfluenza virus with a modified live vaccine. Vet Rec. 2005;157: Davis R, Jayappa H, Abdelmagid OY, Armstrong R, Sweeney D, Lehr C. Comparison of the mucosal immune response in dogs vaccinated with either an intranasal avirulent culture or a subcutaneous antigen extract vaccine of Bordetella bronchiseptica. Vet Ther. 2007;8: Ellis JA, Haines DM, West KH, Burr JH, Dayton A, Townsend HGG, et al. Effect of vaccination on experimental infection with Bordetella bronchiseptica in dogs. J Am Vet Med Assoc. 2001;218: Crawford PC, Katz JM, Pompey J, Anderson TC, Donis RO. Crossreactivity of canine and equine influenza antibodies (Abstract). Proceed Am Coll Vet Intern Med; Gore T, Headley M, Laris R, Bergman JGHE, et al. Intranasal kennel cough vaccine protecting dogs from experimental Bordetella bronchiseptica challenge within 72 hours. Vet Rec. 2005;156: Ellis JA, Krakowka GS, Dayton AD, Konoby C. Comparative efficacy of an injectable vaccine and an intranasal vaccine in stimulating Bordetella bronchiseptica-reactive antibody responses in seropositive dogs. J Am Vet Med Assoc. 2002;220:43-48.

24 1 TRACKING EMERGING DISEASES IN THE ANIMAL SHELTER Patricia Pesavento, DVM, PhD, Diplomate, ACVP, UC Davis School of Veterinary Medicine, Davis, California "Nothing in the world of living things is permanently fixed." Hans Zinnser, Rats, Lice, and History, 1935 Abstract An emerging infection is one that has newly appeared in the population, or one that has existed but is altered in incidence, geographic range, or character (virulent strains, species jumpers). Therefore, while an emerging pathogen can be a novel pathogen, it is often a previously recognized pathogen newly capable of emerging as a virulent species from an otherwise docile/dormant background. In some cases, there are singly identifiable factors associated with emergence (e.g., antibiotic resistance), but many incidences of emergence occur subsequent to alterations in a combination of pathogen, host, and/or environmental factors. Key Content While an emerging pathogen can be a novel pathogen, it is often a previously recognized pathogen newly capable of emerging as a virulent species from an otherwise docile/dormant background. Animal shelters create a uniquely suitable environment for disease emergence: Factors of host compromise and of pathogen virulence should be considered. Clinical presentation of a newly emergent disease, especially if the disease state mimics common diseases (respiratory disease, diarrhea), can be very difficult to recognize. Animal shelters create a uniquely suitable environment for disease emergence. A partial list of factors in the shelter environment that could promote emergence includes transportation, stress (immunosuppression), increased contact (overpopulation), exposure, species mixing, nutrition, concurrent disease, high animal turnover, and indiscriminate use of antibiotics. Selective and enhanced evolutionary pressure on pathogens in an environment with a high turnover of animals on a range of vaccination protocols also plays a role. Figure 1 is a model of the steps required for emergence of a pathogen. Only some of the barriers to emergence are noted: Whether there is a new pathogen, one newly introduced to an environment, or one endemic and behaving in an altered manner, the steps to emergence are similar, complicated, and multiple. Proceedings of a Symposium Held at the 2008 North American Veterinary Conference and the 2008 Western Veterinary Conference. Copyright 2008 Pfizer Animal Health. All rights reserved. The opinions expressed in the articles in this publication are those of the authors and do not necessarily reflect the official label recommendations and points of view of the company or companies that manufacture and/or market any of the pharmaceutical agents referred to.

25 2 Figure 1 Steps to emergence for a new pathogen or a known pathogen with altered behavior. Shelter animal populations have progressively grown in number. The United States currently has an estimated 15 to 25 million animals in shelter situations. As a comparison, the number of dairy cows in the United States and Canada combined is about 9.2 million. For food animals, countries including the United States have an extensive diagnostic surveillance system that focuses on zoonotic, endemic, and exotic disease. The cost of such vigilance is in the millions of dollars and includes federal, state, farm industry, food industry, and research contributions. In contrast, with the possible exception of rabies, there is little coordinated or even predictable surveillance for diseases in intensively housed small animals. Although emergent diseases are rarely predictable, diseases emerging from shelter populations could be devastating to both the animal and human populations. Several zoonoses have already emerged in small animal populations and serve as precedent for this caution. The first report of domestic cats dying from H5N1 influenza virus infection came from Bangkok, Thailand, in February. In this seminal case, all 15 cats exposed to the virus (either by ingestion of an infected chicken carcass or exposure to an infected cat) died with severe pneumonia. The fatal disease in cats is now well recognized in most countries where H5N1 virus is endemic in poultry. Researchers speculate that cats may play a role not just in disease transmission but also in H5N1 virus adaptation to mammals. 1 Another example involves a shelter in Idaho that experienced a slight increase in mortality among their kittens and cats, with no concomitant increase in diarrhea. The cause of the higher mortality was revealed by epidemiologic analysis at the Centers for Disease Control and Prevention, which was investigating 49 human cases of multidrug resistant Salmonella serotype typhimurium. These cases were attributed to exposure to animals from that shelter. 2 This particular serotype of Salmonella has high mortality rate in humans (3% to 4%). At the Shelter Medicine program at UC Davis, we have found that if a pathogen is unusual, or behaving in an unusual manner, understanding the distribution, behavior, and character of this pathogen is critical to early and accurate diagnosis. In short, identification of emerging and reemerging infections depends heavily on good pathology and associated diagnostics. The examples below include information on recent outbreaks of viral and bacterial disease associated with the shelter environment.

26 3 Emerging RNA Viral Pathogens If genetic evolution were the sole basis for emergence, agents of emergent diseases would all be RNA viruses and they would all emerge in shelters. Their potential for genomic variability is staggering. Following is some calicivirus math that demonstrates the theoretical potential for RNA virus adaptation: If you make the following assumptions: 10 9 viral particles/day in an infected animal Mutation rate of RNA pol*= 10-4 Caliciviral genome 7.5 kb Then: (virus/day)*(errors/base pair)*(base pairs/virus) = errors/day (probability of a single point mutation)* (probability of a mutation)* (replications/day) = number of particles made with a particular mutation/day Therefore, if a single (point) mutation was responsible for enhanced virulence, every passage in an animal could result in emergence of virulent isolates. There is, however, a price for such infidelity. First, most mutations result in loss of viability (especially with a streamlined [small] genome like that of calicivirus). The assumed gain by RNA viruses of harboring such a fallible polymerase is that the RNA viruses would be evolutionarily flexible, and many are: severe acute respiratory syndrome (SARS), feline calicivirus (FCV), and influenza are all masters of genetic change. All three have contributed to emergence and persistence. Even in pathogens that rely on DNA polymerases, which have high fidelity to assure faithful transmission of genetic information from one generation to the next, it seems that they have back-up, error-prone polymerase systems when mutation is advantageous. Environmental or nutritional stress can result in alterations in polymerase fidelity. In addition, even if mutations result in enhanced virulence, they would have to be the very viral particle that retains the ability to replicate, egress, transmit, and penetrate a new host. So a single or combination of mutations would more likely compromise overall viral fitness than enhance it. Virus adaptation is determined by more than virulence alone. Feline Calicivirus FCV-related disease causes high morbidity and usually low mortality, with only occasional instances of more virulent disease. FCV is nearly ubiquitous in its natural host population, and it is so common that vaccination with a modified live virus (live-attenuated) vaccine is widely practiced in domestic cats. The vaccine prevents clinical expression of FCV infection but does not prevent infection or viral shedding. Estimates of prevalence (with or without vaccination) are based on detection of virus shed from the oral cavity. In a shelter environment, up to 40% of cats at a single point in time are shedding FCV. If shedding is assessed over a longer time frame, up to 90% of densely housed cats are shedders. 3 Many of these cats are asymptomatic, but the most typical manifestation of infection in the natural environment is oral (especially lingual) ulceration and, solely or in combination with other pathogens, mild upper respiratory tract disease. Acutely ill cats can also present with a variety of symptoms, including limping, and there have been several reports of unusual hypervirulent forms of FCV infection causing pneumonia, neurologic signs, abortion, and systemic disease with high mortality. 4-6 Hypervirulent forms of caliciviruses, in cats and other species, show a sporadic ability to emerge from an otherwise docile background. Twelve independent, highly fatal (hypervirulent), isolates of

27 4 FCV have been confirmed by the UC Davis shelter animal diagnostic team since This is likely to be an underestimate of the total number of outbreaks; samples necessary for confirmation are only available in a percentage of reported cases. Isolates described as virulent have caused a diverse spectrum of illness, including limping, diarrhea, pneumonia, hepatitis, pancreatitis, edema, and hemorrhage and in some documented outbreaks, vaccinated adult cats are more often affected and have a higher risk for severe disease than kittens. 6 In our experience, outbreaks most often emerge after susceptible cats are exposed to a densely populated shelter or to a cat recently from a shelter introduced to a home, a veterinary hospital, or a clinic. Why Hypervirulent Forms of FCV Are Hypervirulent Because hypervirulent isolates of FCV affect cats from diverse environments and because hypervirulent disease has been reproduced experimentally, 4,7,8 we presume that factors associated with the pathogen underlie the wide spectrum of disease associated with FCV. More specifically, we presume that sequence variations in the FCV genome correlate with virulence and clinical expression of FCV. This is far easier to hypothesize than to prove: Single-stranded, positive sense RNA viruses like caliciviruses can undergo rapid mutation for several reasons, including polymerase infidelity. While several studies have attempted to identify any sequence pattern that corresponds to clinical outcome of disease, we have all thus far failed. Nucleotide homology and predicted amino acid similarities are no greater between hypervirulent isolates than between mild field strains: Among any two independent FCV or hypervirulent FCV isolates, there is a sequence identity of approximately 78% to 80%. Many researchers are searching for recognizable differences between the mild field strains of FCV and hypervirulent strains. Traditional pathology has given us some insight. Studies on tissue and cellular distribution of virus during natural outbreaks of virulent disease indicate an increased cellular distribution. Studies on distribution of FCV in cats that are clinically affected with mild field strains of FCV indicate that the virus is limited to mucosal and rarely respiratory epithelial cells. In contrast, in cats naturally infected with a hypervirulent type, termed virulent systemic (VS) FCV, viral antigen is present in endothelial cells as well as in epithelial cells. 9 Much of the range of severe and deadly lesions in VS-FCV affected cats can be attributed to endothelial compromise. Information on the effectiveness of any of the current vaccines to the spectrum of circulating viruses is limited. Emerging Bacterial Pathogens If not absolute, at least profound attention is paid to viruses when emergent diseases are discussed. Recent focus on influenza, SARS, and HIV bolster this impression. Yet, in shelter animal medicine, we have found species jumpers, unique presentations, and fatal isolates among several bacterial genera. The disproportionate threat in human and animal medicine from emergent viruses in some part derives from perceived, real, and anticipated cure for most bacterial diseases. This is probably, both now and in the immediate future, naïve. Consider the current impact of Yersinia pestis, a zoonoses many people consider historic because the largest human infection with Y. pestis occurred in Europe, in the 14th century. This organism causes the plague, which entered the port of Messina, Sicily, and within 5 years killed 25 million people, or 1 in 3, in western Europe. The following quotation (from Allegheny College) on societal impact of the plague discusses the factors in emergence: In the period between 1000 and 1300 Europe's population almost doubled. Driven by a revolution in agricultural technology, this surge in population became a problem when the number of people exceeded the technology's ability to support their basic needs. Increasingly cities relied on the importation of food from further distances. Cheap labor coupled with the high cost of land and food

28 5 led to increased rural migration, often forcing travel to become the only way of life for peasants and field hands. This increased mobility between geographical areas enabled disease and sickness to be easily spread the sinners who displeased God were believed to be more susceptible to infection with the plague. Modern life ensures that contributing factors to precipitation of bacterial outbreaks will become more and more prevalent. Moreover, multidrug resistance is occurring in many bacteria that had previously, and universally, been susceptible to antibiotics. This includes Y. pestis, for which several independent resistant isolates have been described, and many members of the genus Streptococcus. Streptococcus pneumoniae was considered universally susceptible to antibiotics in the 1970s; Figure 2 is a map illustrating the prevalence, in 1997, of penicillin or multidrug-resistant S. pneumoniae. Figure 2 Prevalence of penicillin-resistant Streptococcus pneumoniae as percentage of the total population. S. pneumoniae is a human bacterial pathogen that causes pneumonia, meningitis, and other diseases. In the 1970s, this organism was considered consistently susceptible to penicillin; at present, resistance rates up to 70% are reported among clinical isolates. This figure was taken from Baquero and Blazquez (1997). Streptococcus canis in Cats An emerging infection is one that has newly appeared in the population or a preexisting one that is altered in incidence, geographic range, or character. In the case of Streptococcus canis in cats, emergence is associated with a shift in both character and incidence. S. canis is present in up to 10% of cultures from the nasal cavity of cats with chronic upper respiratory infections, and infection has been associated with epidemics of arthritis, urogenital disease, and neonatal septicemia Most previous reports reflect time-limited outbreaks of disease in young closed-colony animals. Within the past 3 years, the Shelter Animal Medicine Program at UC Davis has seen five independent outbreaks of S. canis infection, affecting over 300 cats (mortality rate of up to 30%). Infection with the bacteria was associated with two distinct clinical courses. One was death associated with necrotizing fasciitis (toxic shock syndrome). In the other, cats presented with multiple skin abscesses and sinusitis that

29 6 intermittently progressed to meningitis. There are several disturbing features of these outbreaks: 1) While the cultured bacteria were susceptible to multiple antibiotics, treatment had varied success; 2) despite extensive cleaning, including cage removal and replacement, the bacteria has persisted in the environment of at least one shelter for over 18 months, with new and fatal cases cropping up within 2 days of placing cats back into the room; 3) cats of all ages, and of all vaccination status, were affected; and 4) in most cases, S. canis was the sole pathogen identified; other pathogens were variably but inconsistently present, and well within the normal ranges for a shelter environment. Assessing the factors contributing to these outbreaks is complicated. Management practices of individual shelters, the stress of captivity, and antibiotic choices and regimen could be confounding or contributing to the course or presentation in these cases. But virulence of the specific species of Streptococcus isolated is likely to be an important ingredient in emergence and reemergence. Preliminary results indicate that the streptococci cultured from the outbreak that has lasted over 18 months have been clonal over the entire period of the outbreak (Byrne B, Sykes J, personal communication). Some investigators have attributed virulence, and more specifically fasciitis, to expression of bacterial enzymes, such as hyaluronidase, which degrade the fascia. A complete understanding of how S. canis causes invasive disease would include analysis of the genetic diversity among these isolated species. This bacteria, although typically considered a commensal and extracellular pathogen in cats, is capable of causing severe life-threatening invasive infections, such as necrotizing fasciitis, sinusitis, bacteremia, and toxic-shock-like syndrome. Streptococcus zooepidemicus in Dogs Following is an excerpt from an article that appeared during the investigation of an outbreak of hemorrhagic pneumonia in dogs. The New York Times, LAS VEGAS, Feb. 15, 2007 An outbreak of disease that national experts say was of an unusual magnitude prompted a week-long closing of the region s main animal shelter and the killing of about 1000 dogs and cats. Disease outbreaks in shelters are not unusual, but this one was especially gruesome because there were so many different illnesses at once, said Dr. Kate Hurley, head of the Shelter Medicine Program at the University of California, Davis, and one of two veterinarians on the Humane Society inspection team. The viruses were Parvovirus, canine distemper and feline panleukopenia; the bacterial infection was a fatal hemorrhagic, or bloody, pneumonia. I m not aware of outbreaks of this magnitude, said Dr. Hurley, a leading national authority who coincidentally will present a day-long seminar on shelter outbreaks in Las Vegas on Tuesday at the Western Veterinary Conference. One of the challenges we had was that they had this unusual bacterial infection that s not been documented in a shelter before, she said. There was some uncertainty of how to best manage that and what best to do. We were in new territory and found it in both cats and dogs. This article appeared in the New York Times this Spring. The unusual bacteria was S. zooepidemicus, which we found in all 12 dogs we examined from the facility. S. equi subspecies zooepidemicus has not been widely recognized until recently as a pathogen of dogs. 12,13 In the outbreak described in the New York Times article above, acute, fatal hemorrhagic pneumonia was observed in over 1000 mixed-breed dogs in a single shelter. Cases occurred during the fall of 2006 and extended into the winter of Affected dogs had hemothorax and acute, fibrinosuppurative pneumonia with large numbers of intralesional gram-positive cocci.

30 7 Beta-hemolytic S. equi subspecies zooepidemicus was solely cultured from lung tissue of all dogs tested. Extensive diagnostic tests revealed inconsistent but potentially contributory co-pathogens in individual cases; however, evidence from clinical, pathologic, and molecular clonality analyses indicate that S. zooepidemicus can be an acutely fatal respiratory infection in dogs (Pesavento et al, article in press, Veterinary Pathology). References 1. Kuiken T, Fouchier R, et al. Feline friend or potential foe? Nature. 2006;440: Wright JG, Tengelsen LA, et al. Multidrug-resistant Salmonella typhimurium in four animal facilities. Emerg Infect Dis. 2005;11: Radford A, Coyne K, et al. Feline calicivirus. Vet Res. 2007;38: Pedersen N, Elliott J, et al. An isolated epizootic of hemorrhagic-like fever in cats caused by a novel and highly virulent strain of feline calicivirus. Vet Microbiol. 2000; 73: Schorr-Evans E, A Poland, et al. An epizootic of highly virulent feline calicivirus disease in a hospital setting in New England. J Feline Med Surg. 2003;5: Hurley KE, Pesavento PA, et al. An outbreak of virulent systemic feline calicivirus disease. J Am Vet Med Assoc. 2004;224: Hoover E, Kahn D Experimentally induced feline calicivirus infection: clinical signs and lesions. J Am Vet Med Assoc. 1975;166: Pesavento PA, Bannasch MJ, et al. Fatal Streptococcus canis infections in intensively housed shelter cats. Vet Pathol. 2007;44: Iglauer F, Kunstyr I, et al. Streptococcus canis arthritis in a cat breeding colony. J Exp Anim Sci. 1991;34: Taillefer M, M. Dunn. Group G streptococcal toxic shock-like syndrome in three cats. J Am Anim Hosp Assoc. 2004;40: Garnett N L, R S Eydelloth, et al. Hemorrhagic streptococcal pneumonia in newly procured research dogs. J Am Vet Med Assoc. 1982;181: Chalker V J, H W Brooks HW, et al. The association of Streptococcus equi subsp. zooepidemicus with canine infectious respiratory disease. Vet Microbiol. 2003;95:

31 1 POTENTIALS AND PITFALLS OF INFECTIOUS DISEASE CONTROL FOR THE PRACTICING VETERINARIAN Kate F. Hurley, DVM, MPVM, Koret Shelter Medicine Program, Center for Companion Animal Health, UC Davis School of Veterinary Medicine, Davis, California Abstract In the world of human health, prevention of nosocomial disease is the subject of scores of articles, journals, and textbooks. Just a quick search on the subject of hand sanitation alone located a listing of over 650 articles. The challenge of nosocomial disease prevention in a veterinary setting is potentially even greater. Unlike most people, our patients roll around on floors and surfaces and subsequently lick themselves all over, effectively coating themselves with and ingesting a myriad of environmental and salivary pathogens. Caring for veterinary patients is a full-contact sport: We cradle animals against our bodies for restraint, transportation, and out of affection. Whatever is on their fur is then cheerfully transferred to our hands, arms, and clothing; and if we re not careful, from there to the remainder of the patients we care for that day. Key Content No single disinfectant is perfect for all situations; factors involved in choosing a disinfectant include the spectrum of effect, activity in the presence of organic matter, whether it has detergent activity (functions as a cleaner as well as a disinfectant), speed of action, method of application, cost, and safety. Clinics should have a variety of cleaners and disinfectants on hand. Cleaning and disinfecting hands, clothing, and feet is just as important as decontaminating the environment. Drying is an important and often overlooked step in decontamination. There are basically three methods for managing hands: gloves, washing with soap and water, and hand sanitizers; although theoretically less ideal than hand washing, hand sanitizing may actually yield superior results if compliance is better. Foot baths are not likely to be fully effective as commonly used; when serious isolation is required, dedicated boots or shoe covers are a much better choice. In light of the ease with which pathogens can be transmitted among animals and onto humans, it would seem that outbreaks of nosocomial disease would be frequent in veterinary clinics unless very rigorous infection control was practiced. However, in reality such outbreaks are mercifully uncommon. Even if infection control is less than perfect, most of our patients are protected by vaccination against some of the most serious threats, and by their own good immune systems against many others. Unfortunately, this is not always the case. In recent years we ve seen the emergence of significant infectious illnesses against which neither vaccination nor overall good health is Proceedings of a Symposium Held at the 2008 North American Veterinary Conference and the 2008 Western Veterinary Conference. Copyright 2008 Pfizer Animal Health. All rights reserved. The opinions expressed in the articles in this publication are those of the authors and do not necessarily reflect the official label recommendations and points of view of the company or companies that manufacture and/or market any of the pharmaceutical agents referred to.

32 2 protective, and we never know when yet another new disease will hit. This poignant e- mail was posted on the Veterinary Information Network in May of 1998: Every veterinary hospital owner's nightmare: I will be composing a summary of now 12 cases, in the last 14 days, of a series of cats with only one common thread...they were in my facility at the time of or within 1 week of getting ill My own cat that was visiting (boarding) died within 48 hours. But this is not your typical URI cat. This is a killer. First 8 cats...7 deaths. This was diagnosed as one of the first known outbreaks of vaccine-resistant virulent systemic feline calicivirus, a condition that attacks and kills even healthy, well-vaccinated adult cats. Canine influenza is another example of a disease that does not discriminate by age, health, or vaccine status. Both diseases have swept through veterinary clinics, causing widespread morbidity, tremendous expense, and the heartbreak of having to tell clients that their pet has died of disease acquired through a veterinary visit. Severe disease has been transmitted when a patient was brought in for something as simple as a weight check. Less dramatic (so far) but still troubling diseases with high potential for nosocomial transmission include zoonotic conditions, such as Salmonella, ringworm, and Giardia. Clearly, as veterinarians the last thing we want is for our patients to go home sicker than when they came to us, especially with a disease acquired during a veterinary visit. A well-crafted plan is needed to guard against such disasters. Consider everything that goes into the decision to choose a particular antibiotic regimen for a patient: The antibiotic has to be effective against the suspected pathogen; it must be administered by the correct route; it must penetrate to the location of the infection; it must be given with adequate frequency for a sufficient period; and measures are sometimes needed to verify cure. There is no one-size-fits-all antibiotic choice. Similarly, when choosing a disinfectant, we must consider the spectrum of effect; method of delivery; constraints against efficacy (such as presence of organic matter); time to effect; and periodic verification that the disinfection program is working as intended. We need to consider numerous aspects of disinfection: hands, surfaces, cages, clothing, and the role of other animals. So, What Disinfectant Should Be Used? There is no simple answer to this question. If you have only one disinfectant on hand, chances are it is not sufficient for every circumstance. Factors to consider include the spectrum of effect; activity in the face of organic matter; whether it has detergent activity (functions as a cleaner as well as a disinfectant); speed of action; method of application; cost; and safety. As with choosing an antibiotic, scientific research should be consulted as well as claims of manufacturers or vendors. Unenveloped viruses are among the most common and challenging small animal pathogens requiring our attention. These include the notorious parvoviruses (canine and feline), as well as feline calicivirus and canine adenovirus. These viruses provide an interesting illustration of the perils of choosing a disinfectant based solely on label claims. Back in 1980, researchers at Cornell noticed that feline calicivirus seemed to spread in their research facility despite use of a disinfectant that was labeled as being effective against that virus. This triggered a research study testing the efficacy of

33 3 quaternary ammonium and other commonly used disinfectants against enveloped (feline panleukopenia, feline calicivirus) and unenveloped (feline herpes) viruses. 1 Disappointingly enough, the quaternary ammonium compounds, which were labeled as being effective against unenveloped viruses, utterly failed to inactivate feline panleukopenia and only partially inactivated the troublesome calicivirus. The authors concluded that A 0.175% sodium hypochlorite solution was the most effective and practical broad- spectrum virucidal product used alone or in combination with other disinfectants/detergents ; good old household bleach diluted at one half cup per gallon outperformed the others in this study. In and most recently in 2002, 3 subsequent studies continued to disprove label claims of quaternary ammonium compounds against unenveloped viruses. This type of disinfectant may eventually be independently proven to be reliable against the unenveloped viruses, but until then it is probably wise to at least follow these products with another, independently documented product. Even the mighty bleach is not without its flaws. It has no cleaning properties and is significantly inactivated by organic matter. Applying bleach to a contaminated surface is unlikely to have the desired effect. Although stable when stored in light-proof containers for at least 30 days, 4 heat and exposure to light can substantially compromise the disinfectant properties of bleach solutions. The quaternary ammonium compounds, despite their weak performance against unenveloped viruses, have strengths that contrast with many of bleach s weaknesses: They do have some ability to act as a cleaner as well as a disinfectant (depending on concentration and formulation); they have better--although not complete--activity in the face of organic matter; and they are relatively stable in solution. Another promising disinfectant is potassium peroxymonosulfate (e.g., Trifectant ). This disinfectant has been independently proven against the unenveloped parvo and caliciviruses, 3 has relatively good activity in the presence of organic matter; and has some cleaning as well as disinfecting properties. Table 1 lists the disinfectants discussed here as well as some other commonly used products and their good and bad points. The bottom line is that no single disinfectant is sufficient for all situations. Potassium peroxymonosulfate may be the best choice to decontaminate a grassy area soiled by parvovirus, while quaternary ammonium may be a fine choice for daily cleaning and disinfecting dog runs where parvovirus is not a concern. Each veterinary clinic should have a small arsenal of disinfectants on hand for various eventualities.

34 4 Table 1 A Time for Everything Most of us are familiar with the general idea that disinfectants require 10 minutes of contact time for best effect. Unfortunately, it s not that simple. Some disinfectants are substantially effective in much less time, and such factors as low temperature and organic matter contamination will increase the amount of time needed. Ten minutes of contact time at room temperature on a clean surface remains a good general rule, but it s not a bad idea to leave disinfectant in contact for up to an hour or more when organic contamination cannot be removed or if temperatures are very low (e.g., cleaning outdoor runs in winter). Timing of the application is also important: Disinfectant works best when

35 5 applied to a freshly contaminated surface. For instance, disinfectant applied to an examination table immediately after use is likely to work better than disinfectant applied just before the next use when whatever has been sneezed, smeared, or otherwise left on the table has had time to dry. Getting the Drug To the Bugs Put a disinfectant that is inactivated by organic matter in a bucket with a mop or rag, mix in some dirt and feces, and you ve got a recipe for disaster. The method of application is just as important as choice of disinfectant. When at all possible, mops and buckets should be avoided. For small cleaning jobs, bottles with squirt tops rather than spray tops are ideal to decrease the amount of disinfect aerosolized into the environment (this is important to protect animal and human respiratory health) (Figure 1). Figure 1 Nubbin top dispenser, preferable to traditional squirt bottles. If this bottle contained bleach, it should be opaque to prevent light-induced degradation. Opaque containers should be used for bleach. The bottles of all disinfectants should be labeled with the identity of the disinfectant; all required safety information; and the date and initials of the person who made up the solution (for accountability and retraining if the disinfectant is incorrectly formulated). For larger cleaning jobs, hose-end foamers or built-in dispensing systems are preferred. For in-between jobs or if use of a hose is impractical, a hand-held or back-pack style pesticide applicator can be used. If buckets must be used, contamination of the disinfectant can be minimized by rinsing the mop or other applicator in a bucket containing clear water between each application of disinfectant. Two-sided buckets are available from janitorial supply houses, or you can simply use two buckets. Separate cleaning supplies should be used for each area to be cleaned. Whatever disinfectant and method of application is used, one key decontamination step- - the importance of which is often underestimated--is drying the environment. Most

36 6 pathogens prefer a moist environment, and if they happen to have slipped past your chemical disinfectant and mechanical removal, they will happily persist for hours or days in a damp corner. Fatal bacterial pathogens have been cultured from pools of water lingering in kennels that had been completely cleaned and disinfected, and even from the disinfectant dispensing system itself in one shelter outbreak. Attention to drying is especially important when the surface to be cleaned is uneven (leaving pools of water even after use of a squeegee) or in humid climates where air-drying may not occur. Getting a Handle on Hands Cleaning contaminated environmental surfaces is less than half the battle. Even if we put an animal onto a perfectly clean examination table, if the hands that hold the animal are dirty, the animal will soon take in whatever was on those hands. Hands also make their way into human mouths (and noses). So, keeping hands clean is important for protection of human as well as animal health. There are basically three methods for managing hands: gloves, washing with soap and water, and hand sanitizers. Gloves are the most fool-proof choice for preventing germ transfer on hands, but they must be changed between each and every animal. Although gloves can be a nuisance, time-consuming and relatively costly, there are times when they are clearly worth the effort. A change of gloves between every animal is indicated when animals that may be infected with particularly environmentally resistant germs are being handled; when a zoonotic infection is suspected; or during any outbreak of unknown disease. For handling that does not require great dexterity (such as carrying cats), a cheap, relatively easy alternative to latex gloves are lightweight food-preparation gloves--basically plastic bags with fingers. These can be found for less than a penny a pair and are quick and easy to take on and off. I used to believe that hand washing was the next best thing when gloves are impractical. However, this point of view is not necessarily supported by the research. It is true that proper hand washing has the significant advantage of removing even the most resistant pathogens and is therefore required under certain circumstances. But it is surprisingly difficult to wash hands correctly, and compliance may not be all one could wish for. Ineffective hand washing may actually be less helpful than correct use of a good hand sanitizer. 5 According to the Centers for Disease Control and Prevention, proper hand washing technique consists of the following: 1. Wet hands with warm running water. 2. Lather with soap. 3. Scrub all surfaces for a minimum of 20 seconds. 4. Rinse. 5. Thoroughly dry hands using two single use paper towels for 10 seconds each--if cloth towels are used, a fresh one must be used for each hand washing episode. Hands should be dried for 10 seconds on one area of the towel, then 10 seconds on a fresh area. As with environmental decontamination, the drying step is especially important. Moisture on hands may actually facilitate pathogen survival and transfer. 6 Clients and staff should have ready access to hand washing stations stocked with soap and paper towels at all times.

37 7 The third strategy for dealing with contaminated hands is those convenient hand sanitizer gels. Even though the spectrum of effect may be limited, a slightly less effective method, used consistently and correctly, will provide better results than the theoretically ideal choice if application breaks down in reality. In one study that compared the bacterial levels on the hands of veterinary students after performing an examination on a horse, bacterial counts were actually lower on the hands of those who used a hand sanitizer than of those who washed and dried with soap and water. 5 The best hand sanitizers for veterinary use (due to better efficacy against feline calicivirus) should contain 60% to 90% ethanol alcohol. They should be used according to directions, which usually involve rubbing for at least 10 seconds then allowing hands to air dry. Alcoholfree products should generally be avoided: In addition to being less reliable against calicivirus, some of these contain phenol (Triclosan ) or quaternary ammonium (benzylalkonium) compounds, which can be toxic to animals at too high a concentration. No hand sanitizer is effective against the most durable pathogens, such as the parvoviruses or ringworm. When these pathogens are suspected, gloves and hand washing are a must. One Foot at a Time In human health care, hands are the primary culprit in disease transmission. For those of us in veterinary medicine, it s not quite so simple. Our patients--especially dogs--often sit on the floor of the waiting or examination room. The way many dog runs are set up, caretakers must walk in and out for cleaning, carrying with them whatever happens to be on the soles of their shoes. Cats, on the other hand, often make their way through a clinic from carrier (or lap) to examination surface to a cage off the ground, consequently leaving them less vulnerable to foot-borne disease. Luckily, if the basic environmental cleaning program is effective, the risk for transmitting disease via footwear is probably not all that high. While it is true that some pathogens may get tracked into a room when staff enters to clean it, if the last step is application of a good disinfectant, whatever was tracked in will be inactivated. If staff changes footwear after cleaning and wears separate footwear for isolation areas, this risk will be further reduced. Foot sanitation should be a greater concern under certain circumstances: before entering areas where vulnerable animals (puppies and kittens) are housed on the ground; when entering and exiting isolation areas where animals are being treated for conditions caused by particularly durable pathogens (such as parvovirus or ringworm); and during an outbreak of unknown cause. There are two general options to prevent disease transmission via footwear: foot baths or dedicated boots/shoe covers. The obvious advantage of foot baths is that they are much more convenient than special shoes or covers. Every single person entering a given area can easily step into a foot bath on his or her way in and out of the room. The disadvantage of foot baths, however, is a big one: They just don t tend to work very well. All disinfectants require some amount of contact time for optimal effect, and this will not be achieved with a quick dip in a foot bath. Disinfectant foot baths are often not of sufficient depth or are not used in a manner that effectively removes gross organic matter, further compromising efficacy. To maximize effectiveness of foot baths:

38 8 Use a disinfectant that is reliably effective against the pathogens that are probably present and that has reasonable efficacy even when contaminated by organic matter. Make sure the foot bath is deep enough to completely cover shoe treads. Provide a stiff bristled brush to remove dirt caught in shoe treads. Change foot baths at least daily or more often if visibly dirty. Clothing: Beyond Fashion Statements So now we ve talked about hands and feet, leaving us only with that troublesome expanse of clothing in between. Even in human health care, disease transmission on clothing is a big concern. For instance, one study found potentially harmful pathogens present on almost half of doctors neckties. 7 Figure 2 demonstrates that clothing-borne disease transmission is a very real concern in veterinary medicine as well: The culture plate depicted was taken from a technician s scrub top after just a few hours of routine work. Figure 2 Bacterial culture taken from a veterinary technician s scrub top after a few hours of routine work. This risk for disease transmission on clothing is enhanced by our patient s propensity to shed hair that is potentially coated with everything from the animal s saliva and environment. Some pathogens may even cluster around hair follicles, facilitating spread on clothing. Ringworm is an obvious culprit, but virulent systemic feline calicivirus also may concentrate around hair follicles. This may partially explain the spectacular ease with which fomites of some strains of calicivirus can spread (Figure 3).

39 9 Figure 3 Virulent systemic feline calicivirus clustered around hair follicles (brown staining indicates presence of virus). One of the most important--and reasonably easy-- infectious disease control procedures is to have staff change clothing or wear protective garments for dirty activities, such as treating of sick animals and cleaning. Although it is obviously not practical to change one s entire outfit with every animal, spare scrub tops or protective smocks should be freely available and used whenever interacting with a potentially infectious or high-risk animal (e.g., one that has just been purchased, adopted, or spent time in a boarding kennel). Discarded surgery gowns are ideal for this purpose, as the long sleeves provide full covering for arms, which can escape both hand washing and gloves. Finally, we come to the matter of laundry. What do you do with all those smocks and tops I encourage you to use so freely? Good news here: the vast majority of the time, all that s required is washing in either a regular or commercial washing machine with hot water and bleach, and drying on heat cycle. No more bleach than the usual amount for a given size of washing machine is needed (half a cup for an average household washer). Although myths persist about bleach being inactivated by laundry detergent or hot water, this is not the case. As long ago as 1938, high temperature laundering with bleach was found to be an effective method of sanitizing hospital linens, and subsequently it was found that bleach used with water temperatures as low as 48 C (118 F) was sufficient. 8,9 An additional measure of safety is provided by the heat and desiccation of drying; for this reason, hanging laundry to dry is less ideal, especially if it is not exposed to direct sunlight (e.g., indoors or in cloudy weather).

40 10 Verifying Cure At the beginning of this article, I talked about antibiotic use and how some measures (such as bacterial cultures) are necessary to verify that our treatment has been effective. Similarly, occasionally reviewing the efficacy of a hospital disinfection program can be a powerful educational and motivational tool for staff. It does not have to be either punitive or costly. One simple method is to streak bacterial culture plates from cages, examination surfaces, and scrub tops--for example, as shown in Figure 2. A sterile environment is not expected, but comparison of culture numbers to a known clean/disinfected surface can be helpful. Another fun tool is glo-germ, a product that fluoresces under an ultraviolet light and that is designed to mimic the spread of germs (available at for under $20 a bottle). This can be used in many ways: for instance staff can handle a glo-germ-spiked stuffed or clinic cat, then wash hands as usual and check for residual germs ; or it can be secretly sprinkled in the backs of cages prior to cleaning, and staff can be rewarded if they successfully get it all out. Preventing Adverse Effects Like many active chemicals, disinfectants are not without the potential for harm. At minimum, use of disinfectants at excessively high concentrations can create respiratory irritation for animals and staff, and some chemicals (such as quaternary ammonium and phenol disinfectants--for example, Pine-sol ) can actually be fatal when applied incorrectly Figure 4 Oral ulcer attributed to improperly diluted quaternary ammonium disinfectant. Figure 4 shows an oral ulcer caused by improperly diluted quaternary ammonium disinfectant; one cat died of pneumonia subsequent to exposure. A more subtle risk is the wasted time and money and false sense of security that comes with an ineffective