Every horse is at risk for infectious diseases.
Take the quiz to learn more about the major equine diseases and some important things to watch. Work with your veterinarian to design an annual vaccine protocol tailored to your horse's needs and unique risks.
Q1. West Nile virus can infect:
ANSWER: D. All of the above
West Nile virus is spread to humans and horses by mosquitoes that feed on infected birds, the main carriers of WNV. Mosquitoes are the major transmitters of WNV between birds, horses and humans.
Q2. The easiest way to help control the mosquito population that puts your horse at risk for West Nile virus (WNV) and Eastern or Western Equine Encephalomyelitis (EEE/WEE) is to:
ANSWER: C. Keep standing water from collecting
Bug zappers might be more exciting, but the simplest and least expensive way to cut down on your mosquito population is to keep standing, stagnant water from collecting in pastures and containers.
Little things, like emptying birdbaths and buckets after storms and cleaning your gutters can help get rid of the standing water where Culex mosquitoes (the species that spread WNV) lay eggs. Fewer mosquito eggs means fewer disease-carrying mosquitoes overall.
Q3. Horses are the most sensitive of any mammal to which of the following diseases:1
Tetanus is caused by soil-dwelling Clostridium tetani bacteria. Horses are the most sensitive of all mammals,
aside from possibly humans, to infection with these bacteria and the tetanospasmin neurotoxin they produce.1
Puncture wounds, exposed tissue, contact with contaminated fencing, surgical incisions and contact with
rusted metal are all ways for tetanus-causing bacteria to infect a horse.2,3 Clostridium tetani bacteria are
found in soil nearly everywhere in the world, which means most every horse is at some risk.1 That's why
annual vaccination is so important.
Q4. True or False: Once rabies clinical signs develop in a horse, there's still time to save the animal.1
ANSWER: B. False1
Sadly, once rabies signs develop in a horse, the disease is invariably fatal.1
The incubation period for rabies is two to nine weeks, after which clinical signs begin to develop.
Survival after the onset of signs is usually only four or five days.1
Q5. How far can droplets from a horse cough travel?1
ANSWER: D. 50 yards1
Droplets from a horse's cough can travel up to 50 yards!1 Pretty amazing - or pretty scary if that horse happens to have equine influenza. But it certainly makes it more understandable that an infected horse may be able to infect at least 10 others.1
If you're going to shows or places where your horse will be around others this year, please be sure to vaccinate. There is no way to be sure that an infected horse won't be stabled right beside yours.
Q6. Which of the following is not true of Potomac Horse Fever (PHF)?1
ANSWER: C. It is caused by a virus carried by many hosts1
PHF is actually caused by Neorickettsia risticii bacteria, not a virus. Despite being named after the
Northeastern river where it was first identified, it has been identified in 43 states and three Canadian
provinces.1 In addition to high fevers and colic, PHF has also been associated with laminitis, depression and
abortion in pregnant mares.1
The complex life cycle of PHF involves flukes, snails and aquatic insects carrying N. risticii bacteria. Since
nightlights attract insects closer to the barn, nightlight use can increase the chances of infected insects
infesting bedding, water and feed where a horse could easily ingest them.
Q7. True or false: There is no definitive test for rabies in live horses.
ANSWER: A. True
Rabies is a complicated neurological disease, and there's not yet a test that can conclusively prove
whether a living horse is infected or not. In order to know for sure, a horse would need to be euthanized
and its brain examined. Wildlife suspected to have rabies must be necropsied in order to be certain.
That's why it's better to play it safe. Horses should be vaccinated every year, and any unvaccinated horse
that is bitten by a wild animal or a horse with unknown rabies vaccination history should be seen by a
Q8. Which of the following diseases is not on the AAEP list of five core diseases for which all horses should receive vaccinations every year?1
ANSWER: C. Equine Influenza1
The AAEP recommends every horse be vaccinated annually against Rabies, West Nile virus, Eastern
Equine Encephalomyelitis, Western Equine Encephalomyelitis and Tetanus.1
Equine Influenza is a serious equine disease that is spread directly from horse to horse. If your horse is
housed in a communal barn or frequently travels to shows or events, talk to your veterinarian for more
information about flu vaccination, as it is likely a good idea.
Q9. Which disease was first identified in America in 1999?1
ANSWER: B. West Nile virus1
Though it was only identified in 1999, West Nile virus has already claimed thousands of equine lives.2
Thankfully, due to vaccination, incidence of the disease has dropped from 15,000 recorded cases in
2002 to less than 200 in 2008.2 But that's no guarantee against future outbreaks.
Infected birds and mosquitoes are found across the country every year, and if vaccination levels drop,
cases of West Nile virus will almost certainly go up. Make sure your horse is protected.
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We hope you learned a thing or two about the disease risks your horse faces. Of course, knowledge only takes you so far, so if you haven't already, talk to your veterinarian to schedule your annual vaccinations.