3. What factors influence your decision when determining the duration of use?

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1 Table 1 Antimicrobials With Approved Therapeutic (Treatment/Control/Prevention) Indications With Undefined Durations of Use in Chickens (Answers provided by AAAP) silent on Infectious Coryza Chronic Respiratory Disease Oxytetracycline Oxytetracycline Any class at any age, although longer lived birds (pullets and breeders) are more at risk of developing Coryza. Oxytetracycline administered by feed for therapy of chronic respiratory disease in chickens already has a specified inclusion rate (400 g/ton) and duration of therapeutic administration (7-14 days). Likewise, oxytetracycline water soluble powders administered for therapy of chronic respiratory disease in chickens already have a specified dosage ( mg/gallon of drinking water) and duration of therapeutic administration (7-14 days). The only level of administration in feed that does not have a specified duration of administration is at g/ton for increased rate of weight gain and improved feed efficiency and those uses will be eliminated with the implementation of GFI209, GFI-213 and the revised VFD starting on January 1, 2017, therefore we will not Infectious Coryza is difficult to eliminate from a flock and frequently becomes a chronic, relapsing flock infection. Consequently, pulse therapy is typically used. Initial treatment is typically days followed by administration for 1 week a Multiple factors can determine duration of treatment, including virulence of the microbe, secondary infections or other stressors, production system in which they are grown (such as access to litter). Again, the month for the life of the flock or organism is typically not as needed. The current eliminated and may reappear clearance limits this drug to use throughout the life of the in birds less than 16 weeks of flock. age, which effectively limits the class of birds to broilers and pullets. Peer-reviewed scientific Pros: Possibly by minimizing exposure literature, Diseases of Poultry, resistance can be minimized. Limiting the other Board Certified Poultry duration of therapy to only that necessary to eliminate or control the infection represents judicious use principles in practice. Cons: Strict limitation on the duration of use further limits tools for poultry veterinarians in an already severely limited tool box. Not allowing the veterinarian to utilize his/her judgment and skills regarding duration of treatment and re-treatment if needed may result in more treatment failures, animal suffering, economic losses, submission of affected flocks for slaughter, and resort to more medically important classes of drugs to control infections. Animal Welfare/ Wellbeing could suffer if disease is not alleviated in the allowed timeframe outlined. Increased use of medically important antibiotics due to drug failures or reoccurrence in the same or subsequent flocks due to inadequate control in the current flock. When treatment failures occur, clinicians will be forced to shift to other medically important medications. Pharmaceutical alternatives (sulfonamides, erythromycin and tetracyclines) are available, but they are also medically important. Vaccines are also available for prevention. Infectious Coryza is uncommon in commercial flocks, and it is not feasible or warranted to practice widespread vaccination. Sporadic introductions, typically from non-commercial birds, do occur, and the disease can be devastating when it does occur, so continued access to treatment options is needed.

2 Necrotic Enteritis/Colibacillo sis This disease can be seen at any time in broilers; however, it is typically noted in birds less than 10 days of age and again in birds greater than 28 days up to market age. For therapy it is typically administered for 7-10 days from the onset of clinical signs. Response to therapy is the Peer-reviewed scientific primary determining factor. literature, Diseases of Poultry, Additionally the course of other Board Certified Poultry treatment may be influenced by the animals ability to clear the primary viral insults, other stressors, and additional secondary infections. For prevention and control, the present during the at-risk period. All known alternatives are also medically important. Vaccination with an E. coli vaccine for prevention has been used and at times, even in the face of the disease but it is not always effective. Lincomycin Virginiamycin Potentially at any time, but typically the disease is seen in broilers and pullets between about 10 to 35 days of age. Treatment is typically administered for 7 days. For treatment, the response is usually quite rapid, but relapses are common unless treatment is continued for a sufficient period, which is typically 5-7 days. Relapses after the initial treatment period can occur and will require additional therapy. For prevention/control, the Peer-reviewed scientific literature, Diseases of Poultry, other Board Certified Poultry Bacitracin is a non-medically-important alternative, but it is not always effective. Ionophores, for coccidiosis control, can aid in control of NE as well, but if NE occurs while using ionophores, treatment alternatives are needed. The other known alternative medications (tylosin or penicillin in water) are medically important and penicillin in this regard is extra-label. b. Avilamycin is a new animal drug used for prevention of mortality associated with NE. Fowl Cholera Typically Fowl Cholera is seen in birds greater than 5 weeks of age and can be seen throughout their lifetime; it is typically a disease of older aged birds. Typically therapy is administered for 10 days. Treatment response is usually Peer-reviewed scientific rapid, but relapses are literature, Diseases of Poultry, common (perhaps due to other Board Certified Poultry persistence in the environment, feral animals and rodents in the vicinity of a case, etc.). Development of chronic forms is another concern, so therapy needs to be long enough to reduce the chances of chronic carriers. a. All known medical alternatives are medically important. b. Control and prevention relies on vaccination and biosecurity. Vaccination is typically effective, but is somewhat serotype-sensitive, so that unusual serotypes can occasionally cause disease. Treatment options are therefore still necessary. Gastrointestinal (GI)-Hygromycin B Parasites 1 The birds are at risk of developing the disease anytime they are in contact with the eggs of the parasite. Very little immunity is developed in the birds so they are at a constant risk of developing disease. Hygromycin is labeled for control therefore it needs to be present in the intestinal tract whenever birds are exposed to the parasite eggs. Due to the mode of action of the medication, pulse therapy is not recommended. Parasite burden, age at which medication is started, exposure to parasite eggs, production system (cage, colony or floor rearing), immune system, other stressors. Peer-reviewed scientific literature, Diseases of Poultry, other Board Certified Poultry No other in-feed medication exists for the control or treatment of these parasites. Water soluble anthelmentics are on the market, but few are labeled for poultry and many are ineffective. Therefore the industry has relied on extra-label use. Within the last year, there has been one new medication that is labeled for treatment of major worms in poultry. All water soluble products are for treatment and not prevention or control.

3 Coccidiosis Broilers are susceptible from placement through slaughter. Pullets are typically at risk up until 16 weeks of age. For prevention or control, the medication would need to be in place during the risk period. When used for treatment, it is typically administered for 5-10 days. For treatment, the response Peer-reviewed scientific is usually quite rapid (3 days), literature, Diseases of Poultry, but relapses are common other Board Certified Poultry unless treatment is continued for a sufficient period, so we typically treat for 5-10 days. Even with this treatment regime occasionally birds will relapse and additional treatment is needed. For prevention/control, the For prevention, ionophores and chemical anticoccidials along with vaccination are used. Regarding treatment, amprolium or sulfa medications are used; however, sulfas are also medically important. Vaccination is also utilized.

4 Table 2 Antimicrobials With Approved Therapeutic (Treatment/Control/Prevention) Indications With Undefined Durations of Use in Turkeys (Answers provided by AAAP) silent on Coccidiosis Fowl Cholera In turkeys, from placement through 12 weeks of age. Typically this is seen in birds greater than 5 weeks of age and can be seen throughout their lifetime; it is typically a disease of older aged birds. Turkeys are more susceptible to the disease. It is not typically administered for coccidiosis prevention except when other anticoccidials fail, then it should be used from day of age to 12 weeks. When used for treatment, it is typically administered for 5-10 days. Typically therapy is administered for 10 days, however, relapses are common and treatment may have to be repeated. For treatment, the response Peer-reviewed scientific is usually quite rapid (3 days), literature, Diseases of Poultry, but relapses are common other Board Certified Poultry unless treatment is continued for a sufficient period, so we typically go for about 5-10 days. Even with this treatment regime occasionally birds will relapse and additional treatment is needed. For prevention/control, the Treatment response is usually Peer-reviewed scientific rapid, but relapses are literature, Diseases of Poultry, common (perhaps due to other Board Certified Poultry persistence in the environment, feral animals and rodents in the vicinity of a case, etc.). Development of chronic forms is another concern, so therapy needs to be long enough to reduce the chances of chronic carriers. Pros: Possibly by minimizing exposure resistance can be minimized. Limiting the duration of therapy to only that necessary to eliminate or control the infection represents judicious use principles in practice. Cons: Strict limitation on the duration of use further limits tools for poultry veterinarians in an already severely limited tool box. Not allowing the veterinarian to utilize his/her judgment and skills regarding duration of treatment and re-treatment if needed may result in more treatment failures, animal suffering, economic losses, submission of affected flocks for slaughter, and resort to more medically important classes of drugs to control infections. Animal Welfare/ Wellbeing could suffer if disease is not alleviated in the allowed timeframe outlined. Increased use of medically important antibiotics due to drug failures or reoccurrence in the same or subsequent flocks due to inadequate control in the current flock. When treatment failures occur, clinicians will be forced to shift to other medically important medications. a. Vaccination (limited availability of single USDA approved supplier). b. Medical alternative is limited to a few other FDA approved anticoccidials. a. All known medical alternatives are medically important. b. Control and prevention relies on vaccination and biosecurity.

5 Table 3 Antimicrobials With Approved Therapeutic (Treatment/Control/Prevention) Indications With Undefined Durations of Use in Sheep (Answers provided by subject matter expert on the AALC and reviewed by the COA ) silent on Vibrionic Abortion Chlortetracycline Late gestation (late 2 nd through 3 rd trimester) 2-3 weeks Age of animal Presence of disease/clinical signs Medicating for disease prevention Past personal experience Veterinary medicine magazines Online resources (vet chat groups) Short of duration of treatment can lead to antimicrobial resistance as long duration. Should be decided by veterinarian. Vaccination Enterotoxemia Chlortetracycline Feeder lambs 2 week treatment period in all in/all out feeding lots. Age of animal Presence of disease/clinical signs Medicating for disease prevention Past personal experience Veterinary medicine magazines Online resources (vet chat groups) Short of duration of treatment can lead to antimicrobial resistance as long duration. Should be decided by veterinarian. Vaccination