Disease Doesn't Take a Holiday
You may have heard about the recent and devastating outbreak of Equine Herpes Virus encephalopathy (EHV-1) in a stable not so very far away from yours. This kind of medical problem can happen to any of us, but it is more likely to involve public stables and those facilities where horses frequently come and go. It's a reminder that biosecurity is a "thing" and it needs attention. Each stable is unique both in physical design and character but all will benefit by considering how to deal with the threat of communicable disease within and outside the facility.
EHV-1; Quick Review
Equine Herpes Virus is specific to horses. There are multiple forms of the virus, the type I (EHV-1) virus includes a "latent" (not infective) form. Think of this latency as similar to the human herpes virus that causes "cold sores" which come and go, seemingly associated with stress. The fascinating thing is that the virus is able to "hide" from even a healthy immune system, it's never really gone even when you have no symptoms. Science does not know exactly what triggers the switch from latent to active (disease causing) forms, but stressors of many sorts are implicated. For horses almost anything can cause stress, shipping, showing, heavy exertion, other disease or even psychological trauma are all stressors. It's everywhere, most horses have been infected with this virus at some point in their lives, most often without any overt signs of disease or with mild respiratory "cold" symptoms. Horses that carry the latent virus are normal.... until they're not, if and when the virus becomes active. The active virus is contagious, transmitted via nasal secretions and by extension, anything that those secretions may touch (called fomites). Fomites include buckets, bits, brushes, blankets (etc. continue down the alphabet) and HUMANS. We can inadvertently transmit the virus by being exposed (hands, clothing, boots etc.) to a sick horse then carrying the virus to healthy animals, possibly at another stable or farm. Hand washing, clothes changing and foot baths are important to keep ourselves from spreading disease.
EHV-1 is the virus most often implicated in the neurologic form of infection, called EHM or equine herpes myeloencephalopathy. Neurologic signs may include hind limb weakness, incoordination, urine dribbling etc. Available vaccines for EHV are not considered protective against disease but they may decrease incidence, severity and virus shedding. Similar to childhood vaccination in humans, vaccinating your horse may help other horses as much as your own.
What's happens in EHM is the virus damages small blood vessels in the brain and spinal cord. Subsequent blood clots restrict blood supply which leads to tissue death and a variety of clinical signs depending on exactly where the damage occurs. This mechanism of action could be considered similar to what happens in a heart attack or stroke. Treatment is supportive; maintain hydration, decrease fever and inflammation, support neurological functions. They're working on anti-virals but none are available as yet, another reason that prevention is the best treatment. When disease strikes, isolation, containment, quarantine and bio-security measures are best practices to limit the outbreak... and the heartbreak.
What You Can Do
You can't always avoid medical challenges in your animals but you can be pro-active about planning how to deal with them. You can educate yourself and follow through on general wellness protocols, including vaccination, deworming, dental and wellness checks. You can consider health hazards that your particular animals might face in the course of a year and develop plans to mitigate them. You can pay attention to the habits, moods and physical condition of each individual animal daily or multiple times a day if anything looks awry. You can learn how and when to take a rectal temperature and know the normals. (
click here for a quick review)
Now is a good time to get up to speed on health care plans for the whole year especially if you have traveling, showing or breeding on your calendar. Timing can be important for vaccinations, doing dental work or meeting travel requirements. Let's work together to make 2018 a healthy, happy year for all the animals.
This won't be the last....
Guidelines for managing contagious disease outbreaks
(Recommendations from the WA State Veterinary Medical Association.)
Given the highly infectious nature of the virus, here are some strong recommendations for horse owners.
Closely observe your horse and look for signs of possible infection, which include:
· Fever of 102.5 degrees F or higher.
(Note; in our experience, a fever of 101 degrees F in an adult horse should get your attention and should be monitored, if consistent, consult with your vet.)
· Discharge from the eyes or nose
· Respiratory symptoms
· Swelling of the limbs
· Spontaneous abortions
· Neurological signs such as unsteady gait, weakness, urine dripping, lack of tail tone and recumbency.
Be sure to obtain and record the body temperatures of all horses on the premises twice daily, ideally first thing in the morning, and last thing at night, and before administering medications as some medications can lower body temperature.
Most importantly, if you detect any of the symptoms above, notify your veterinarian immediately. Your veterinarian may want to take nasal swabs for virus detection or blood samples for evidence of exposure to EHV – 1.
Although there are several EHV – 1 vaccines available in North America that control respiratory disease and/or abortion in horses, none of the vaccines provide protective immunity against EHV – 1, neurotropic form.
To protect your horse from becoming infected and help limit the potential spread of this virus, here are several things all horse owners should be doing.
1. Monitor all horses on your premises for the previously described symptoms.
2. Limit direct horse-to-horse contact.
3. Limit stress to horses.
4. Don’t share equipment between horses.
5. Clean barn areas, stables, trailers or other equine contact surfaces thoroughly, removing all organic matter (dirt, nasal secretions, uneaten feed, manure, etc.) before applying a disinfectant. Organic material decreases the effectiveness of disinfectants. Mix disinfectants according to the manufacturer’s recommendation and follow their recommendations for contact time.
6. Use footwear disinfectant and hand sanitizer when moving between areas.
7. If you have a potentially exposed horse, restrict human, pet and vehicle traffic from the area where the exposed horse is stabled.
8. Clean all shared equipment and shared areas, again removing dirt and manure before application of a disinfectant.
9. Self- quarantine any horses with possible symptoms away from other horses and contact your veterinarian immediately.
The time between exposure and illness from EHV – 1 can vary from two to 14 days. By self-quarantining animals with possible symptoms, practicing good biosecurity on the farm, and during travel and contacting your veterinarian as soon as you suspect possible symptoms, horse owners can do a lot to prevent further spread of the virus.
Dr. Brian Joseph, State Veterinarian (edited for length)