September 25, 2008 Understanding Equine Rabies Q: Can wild pigs carry rabies? A: I do not know why they could not carry this virus. Q: Are there disadvantages to administering the rabies vaccine? is there any reason not to vaccinate? A: There are no major disadvantages to vaccinating horses other than loss of possible protection to a fatal disease. I would vaccinate in all cases of my horse. Q: Is there any type of post-exposure (bite from possible rabid animal) prophylaxis for horses? A: Yes the horse could be booster vaccinated and isolated under careful observation for 45 days. Q: Has there ever been any documented cases of a horse surviving rabies or would such a thing be possible to document? A: I know of no reported cases and it would very problematic to even attempt this as it would very likely put many people at risk during the treatment process. Q: What are the statistics for the transmission of rabies to vaccinated horses verses unvaccinated? For all of the articles I ve read, they never say which infected horses had been vaccinated. A: I am unaware of any cases in fully vaccinated horses Q: Why is an equine rabies vaccine necessary once a year? A: Because of the exposure opportunities Q: In most of species, biting is the characteristic sign of rabies. Why is that (i.e. How does the rabies virus stimulate biting in general) A: rabies affects the nervous system and result in many signs some of which include abnormal behavior and with this a horse affected with rabies might bite out of frustration, aggression, stupor or even as a result of paresthesia, where it has abnormal sensation. In this case the horse may actually self-mutilate. Q: I know yawn is a specific sign of rabies in camels. Does this sign exist in case of horse. A: Yawning is a sign often associated with abnormal behavior as a result of neurotransmitters in the brain being activated due to disease or illness such as liver disease, sometimes intestinal disease and therefore yawning may be seen with many diseases which affect the cerebral cortex in horses. Q: Since there is now a rabies vaccination for horses is there any problem switching to this vaccine when For more information on equine health, care and management, visit TheHorse.com 1
my horses next vaccinations are due? A: There are several approved products for vaccination against rabies and effectiveness of them should be comparable.there should be no problem switching from one approved product to another although one should always remember that whenever any vaccine is utilized it is important to follow the manufacturer s recommendations for the use of this vaccine which means that an initial vaccination followed. Q: What makes this vaccine better than what we ve used for years? A: The efficacy of all approved products should be similar. One of the newest products has a 1 ml rather than 2 ml dose and one advantage might be less reaction at the site of injection.. Q: How long does it take to show signs of rabies after being exposed? A: Following exposure the onset of clinical signs can be somewhat variable and has been reported to be fairly long in some horses, however in most horses onset of clinical signs will be within 5 to 7 days following exposure. However if a horse is suspected to have been exposed to a rabid animal it is recommended that the horse be isolated from all other horses and animals and kept under careful observation for a period of 45 days. Q: What are the clinical signs of rabies? A: The signs of rabies can be variable, and may include abnormal behavior including very aggressive nature to stupor or dumb but can also include signs such as obscure lameness, self-mutilation and even colic-like symptoms. Q: Do rabies vaccines have to be actually administered by a vet, or can I buy it from the vet s office and give it myself? A: This vaccine must be administered by a veterinarian. Q: How often should you have your horse vaccinated? A: At the current time all products are administered on an annual basis. Q: What is the treatment for rabies? A: There is no treatment for rabies Q: Can a horse give rabies to another horse? A: To my knowledge there are no reports of one horse giving rabies to another horse but this is possible. Q: What should you do if you suspect that your horse has rabies? A: Any horse that you suspect may have rabies should be immediately isolated form all other horses and animals. The horse should be carefully observed for a period of at least 45 days. In addition an accurate list of all exposed or potentially exposed persons should be maintained. Q: How should you handle him to keep from getting it yourself? For more information on equine health, care and management, visit TheHorse.com 2
A: To keep from getting exposure from your horse you should avoid contact with the horse as much as possible and especially avoid any contact with saliva or blood from the horse. Keep it isolated with food and water available at all times. The horse should be examined daily for any signs of neurological disease and if observed one should consider euthanasia. Q: For some vaccines such as flu, my vets tell me not to work him hard for the next day or so. Should I be backing off his work load after a rabies vaccine as well? A: This is probably good advice following all vaccinations. Q: If my horse is stalled most of the time, should I worry about him getting rabies? A: The usual hosts to transmit rabies, skunks, foxes, raccoons can get in stalls as well as the field, although the likelihood of exposure is lees in this situation. Q: How long can the rabies virus survive outside of a rabid animal? A: Not very long as the virus makes an initial replication in the exposed animal at the site of the bite. Q: What s the best way to isolate a horse that is suspected of rabies infection? A: Isolations should be 35 to 45 feet from all other animals in a sturdy solid wall stall or round pen. Q: What are some of the precautions you should take if you think your horse is infected with rabies? A: If you think your horse may be infected with rabies extreme caution is imperative. Have your veterinarian examine the horse as soon as possible and carefully explain the suspected exposure. If a rabid animal has been found in the pen or corral where your horse is kept your horse should be isolated and handled by very few individuals. The recommendation is to observe the horse for a period of 45 days. Q: With dogs, people are usually told to observe them for 10 days. Should owners do the same with horses? A: For horse the recommendations following an exposure is to observe then for 45 days. Q: So the only test for rabies is post-mortem? A: Yes. Q: What wild animals are most likely to carry rabies? A: Skunks, raccoons, foxes, Q: What areas of the country have the greatest risk for rabies infection? A: Do horses have to be vaccinated for rabies to go outside of the country? Q: Are there any side effects to the rabies vaccines? A: Perhaps some reaction at the site of injection such as mild soreness For more information on equine health, care and management, visit TheHorse.com 3
Q: How is the rabies vaccine given? In the muscle? A: Yes Q: How much does it cost to vaccinate a horse for rabies? A: It might vary depending on the region of the country but will generally inexpensive. Q: Do horses have to be vaccinated for rabies to go outside of the country? A: Not at this time Q: Living in California (particularly the SF bay area), I had always heard that rabies is practically nonexistent or not very common, therefore not a shot that horses need. Now I hear that some vets are recommending rabies shots for horses in this area. Can you explain why this is being suggested now? A: The most likely reasons a veterinarian would recommend this are recent evidence of increasing numbers of rabid animals in the area, the availability of safe effective vaccines and the fact that this is always a fatal disease. Q: Why is it that we as horse owners can not administer Rabies vaccine that is labeled for Equine use? I fully believe that if horse owners were allowed to give their horses the rabies vaccine in the same way as the West Nile, Tetanus etc. then more horses would be protected A: Because this disease is always fatal it is important that every aspect of responsibility for handling the vaccine from storage to administration be the responsibility of the veterinarian. Q: Does the new vaccine have less/different side effects? A: I do not know the answer to this but I suspect there may be because of the smaller dose 1 ml versus 2 ml Q: is rabies is a death sentence to an older horse (20 yrs old)? A: It is a death sentence to all horses. Q: do they have to be bitten to contract it? A: This is the most likely way, although any very close contact with saliva from a rabid animal might be a source of exposure. Q: What s the treatment plan? A: There is no treatment. Q: Could you please discuss adverse reactions-including laminitis-as a possible sequela of rabies vaccination and what, if anything can be done to avoid such problems? A: Because horses are large but fragile they can sometimes develop an adverse reaction to any injection and laminitis is always a concern. I do not know of any precautions to avoid all untoward reactions. For more information on equine health, care and management, visit TheHorse.com 4
Q: Do you think that the AAEP and AVMA should actively lobby to require certificate of Rabies Vaccination for horses exhibited at public venues? A: I think this is a good idea. Q: Why does my horse need a rabies vaccine every year when my dog needs it only every three years? A: At this time there it is thought that because horses are outdoors, sometimes 24 hours a day and in the location where the exposure is more likely than for a dog. Thus it is thought that annual vaccination is important in horses Q: Don t dogs get more cases of rabies percentage wise then equines? A: I am not sure whether this is the case, however I suspect there are many more dogs in the world than horses Q: Is there a better time of year to vaccinate for rabies ie. Spring or Fall? A: Most pregnant mares should be vaccinated prior to foaling which would be in the Spring. Q: I have heard that it is it possible that your horse can be bitten from a rabid animal on a lower limb such as a hind leg and never get the disease if the bite is small? Or is that false? A: Uncertain about this, because to my knowledge it has not been documented, however the bite needs to be significant enough to result in virus entering the tissues in sufficient quantities to replicate, so I suppose this could happen Q: Is the vaccination for rabies recommended to be given more than once a year? A: No just once a year except at the initial vaccination where a 3 shot series is indicated Q: Is the vaccine 100% effective against the horse or animal from getting rabies? And if not, what are the benefits from receiving the vaccine? A: I suppose No vaccine is 100% but rabies and tetanus are very very effective and protective. Q: If my horse is evacuated during a disaster, will a rabies shot administered at the shelter be effective? A: If your horse has been previously vaccinated it should be protected, if this is a first time vaccination then there are a series of shots necessary Q: Is it possible for all blood work to come back normal, yet still have Rabies? A: Probably this could happen, especially early in the disease Q: A yearling at the barn our horses are boarded at came in this past weekend and began showing lameness, then wanting to eat but not eating, then banging himself into the side of his stall, then acting blind, then he died - within 4 days. The vet who examined him just thought it was something neurological but he wasn t overly concerned. A: Perhaps this would be worth considering rabies For more information on equine health, care and management, visit TheHorse.com 5
Q: I have been told that rabies in horses is not a big issue in Utah. Is this true? A: the likelihood of disease is dependent on the likelihood of exposure, does Utah have very few wild animal reservoirs? Q: Why is it so difficult to find a cure for rabies? A: The virus results in significant damage to the nervous system and treatment has been directed and stopping the damage to the CNS is what has been attempted in people. Q: What if the farm the horse is on has fencing that prohibits getting through the fieldsl i.e., wooden fencing with square wire fencing on one side? This would keep skunks, raccons, etc. from traveling through the fields. A: Hopefully this would prevent the wild animals from getting into the field, but I would still recommend vaccinating the horse. Q: How often do they need to be vaccinated against Rabies? A: Annually Q: If a rabied animale drinks from a water trough, can a horse get rabies this way if he drinks from the same trough? A: This is very unlikely because the virus would not survive in the environment and the dilution would likely be a factor. Still I would watch this horse for 45 days. Q: Do you advocate use of gloves whenever examining any animal with neurologic signs with possibility of exposure, i.e., outdoors with wildlife? (Handler in video is leading horse without gloves.) A: Yes Q: Do blood tests show any indications, if the horse is positive for rabies? A: Not to my knowledge Q: Will this ever be included in the 3-way, etc? A: I don t know if it would ever be included in the 3-way (it would be very nice), but in one company it is combined with Potomac horse fever. Q: If you obtain a horse that seems to have similar symptoms but you have no history to know if they could have been bitten by a rabid animal then what would you do to differentiate or at least get enough leading indicators to differentiate? A: The diagnostic evaluation of horses with ataxia along with cerebral signs would be the same. If I was unsure about an exposure to rabies I would do the diagnostic evaluations including neurological examination, head and spinal radiographs, CSF analysis and following this isolate the horse and observe carefully for 45 days. Q: Do blood tests show any indications, if the horse is positive for rabies? For more information on equine health, care and management, visit TheHorse.com 6
A: Not to my knowledge. Q: Could you mention prevention procedures for the handling of suspicious cases, PPE (personal protective equipment), cleaning and desinfection, etc? A: eye goggles, face shield/mask, gloves, and coveralls or a protective gown. The organism does not live long in the environment and is very fragile thus a good detergent to clean with would be Tide followed by dilute bleach as a disinfectant. Q: Is it true that rabid animals do not drink water? A: Rabid animals show very many clinical signs including sometimes difficulty with drinking and swallowing. Q: What ways can you contract rabies? A: This virus requires direct exposure to the virus and so a bite is most likely but if you had some other way of significant exposure there might be other ways of becoming infected. Q: How long before they die? A: The horses usually die within 5 days after clinical signs are apparent. Q: Is rabies a reportable disease to state vets? A: Yes in certain states. Q: And are there statistics for states for the laymen to see? A: There is information available on the National Animal Health Monitoring System web site. Q: When do you recommend the first rabies vaccine for a foal from a vaccinated mare? A: At 6 months of age the second should be 4 to 6 weeks later and final dose at 10 to 12 months, then annually. Q: For an unvaccinated mare? A: Series of three shots beginning at 3 to 4 months of age second dose 4 weeks later, and third at 10 to 12 months of age. Q: how effective is rabies vaccine? A: VERY EFFECTIVE Q: How long does it take for a horse to show signs he has rabies? A: Variable but usually within 1 to 2 weeks but can be longer. Q: Is there any type of post-exposure (bite from possible rabid animal) prophylaxis for horses? For more information on equine health, care and management, visit TheHorse.com 7
A: Yes the horse could be booster vaccinated and isolated under careful observation for 45 days. Q: We live in the country where there are skunks, bats, owls and an occasional bear or mountain lion. There are also elk, deer, and antelope. Do you recommend that our horses receive a rabies vaccine? Thank you A: Yes I think this would be a good idea to vaccinate. Q: Can rabies be contracted by anything other than a bite from an infected animal? A: It requires a significant exposure to the virus in tissues than can have the virus replicate and then enter the CNS. Q: I used to vaccinate my childhood pony (now retired) against rabies. I stopped several years ago after he had a very poor reaction to receiving the rabies vaccine. He became very depressed, stopped eating, ran a fever, and developed a large, hot welt at the injection site. This lasted for several days. He had poor reactions in the past, but this one was the most severe. I have since stopped vacinating him against rabies. Why does this reaction occur in some horses? A: We are uncertain why this problem might occur but it is likely in response to the adjuvant in the vaccine Q: If my horse is evacuated during a disaster, will a rabies shot administered at the shelter be effective? A: If your horse has been previously vaccinated it should be protected, if this is a first time vaccination then there are a series of shots necessary. Q: Is it possible for all blood work to come back normal, yet still have Rabies? A: If your horse has been previously vaccinated it should be protected, if this is a first time vaccination then there are a series of shots necessary. Q: Is it possible for all blood work to come back normal, yet still have Rabies? A: Probably this could happen, especially early in the disease. Q: A yearling at the barn our horses are boarded at came in this past weekend and began showing lameness, then wanting to eat but not eating, then banging himself into the side of his stall, then acting blind, then he died - within 4 days. The vet who examined him just thought it was something neurological but he wasn t overly concerned. A: Perhaps this would be worth considering rabies. Q: With a possibility of an extensive incubation time, how would you know if a horse will develope the disease? If you immunize an exposed animal is it then immune? A: This is a very good question and because there have been a few recognized cases with long incubation periods you need to stay vigilant and alert whenever CNS cases occur. Q: what about the vacines that are good for 3 years or more? For more information on equine health, care and management, visit TheHorse.com 8
A: These are for canine species however I will investigate this further and get back to you next week in the archives Q: Could you mention prevention procedures for the handling of suspicious cases, PPE (personal protective equipment), cleaning and desinfection, etc? A: minimal number of persons should handle or be exposed to the horses and then wear gloves and barrier clothing and generally be very cautious around the horse and avoid contact with blood, saliva or other secretions. Q: Have there been any documented instances of equine rabies epidemics, and under what conditions did that or might that occur? A: discussed one farm in South America where there were several affected horses on the farm at one time. Q: would you recommend vaccinating more than once a year? A: Not after the initial three shot series, or if you had a known exposure, then you would booster and watch. Q: will a horse that has been vaccinated for rabies not contact rabies? A: the vaccine is very effective and will likely be protective. Q: What is the incidence of the dumb versus the violent form of rabies in horses and other equines? A: Much more common to see the stuporous form in horses? Q: I notice the vet. handling the infected horses do not wear any protection againest being bitten by the horse. Why? A: This is an oversite by the veterinarian. Protection should be worn when handling these animals. Q: Is there anytime in gestation that you can vaccinate a pregnant mare? At what age can you vaccinate foals? A: Pregnant mares can be vaccinated 4-6 weeks prior to following. Foals born to mares that were vaccinated against rabies can start the intial series at 6 months of age. A foal born to a mare that was not vaccinated should start the initial series at 3 to 4 months of age. Q: If a horse has been vaccinated annually all his life and is exposed to rabies is the horse safe from getting the disease? A: It is very likely protected so the correct thing to do would be to booster, isolate and observe for 45 days. Q: Is there any test to find out the level of rabies vaccine in your horses system? A: I do not know of people examining post vaccination titers Q: What about California? For more information on equine health, care and management, visit TheHorse.com 9
A: I do not know details but if there are reservoir hosts then the horses should probably be vaccinated. the AAEP guidelines now include it as a part of the CORE vaccinations Q: ours never had the 3 set of rabies shots, do you recommend it now? they are both 2 A: At this point I would simply perform the annual vaccination according to the product label. Q: Does This virus show in the brain as plaque similar to MS in humans? A: I do not think this looks similar to the lesions of multiple sclerosis in humans, the diagnosis is confirmed by the presence of inclusions in the hippocampus. For more information on equine health, care and management, visit TheHorse.com 10