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August 10, 2006

Beware of EVA!

Although infrequent in occurrence, this is one virus that could affect the future of your breeding program.

Equine Viral Arteritis (EVA) is an infectious viral disease of horses and other equines that causes a variety of symptoms, most significantly abortions. Many horses that get EVA exhibit flu-like symptoms for a short time. Although some infected equines never show any noticeable symptoms, this nasty bug can cause one or more of the following symptoms:

1. Fever
2. Loss of appetite
3. Depression
4. Nasal discharge
5. Swelling or edema in the legs, scrotum, sheath or mammary glands
6. Conjunctivitis that may be accompanied by swelling around the eyes
7. Abortion
8. Pneumonia in very young foals.

EVA can be transmitted through both the respiratory and reproductive systems.

EVA is especially bad news for pregnant mares/jennets and mature breeding stallions/jacks! If the mare/jennet is pregnant when she gets infected with EVA, there is a high chance she will abort her foal. She can also spread the virus to her herd mates, causing many of them who are pregnant to abort, too.

Once mares/jennets have recovered from the acute stage of the illness, they will still shed the virus for a couple more weeks. Once they have fully recovered, they will no longer shed the virus, and can be re-bred. They will have no future reproductive problems relating to the virus.

Breeding stallions/jacks, on the other hand, will often have the virus settle in their reproductive tract and will continue to shed the virus in their semen for years to come, and sometimes for the rest of their life. If they are then bred to an EVA-negative mare/jennet, that mare/jennet will get sick with the illness and spread it to her herd mates and the cycle starts over.

There is an EVA vaccine available that has been used in certain breeds in the horse industry for quite a while. If you have a breeding jack or stallion that may be at high risk for picking up EVA at a show or from outside mares coming in for breeding, you may want to consider talking to your vet about vaccinating him if he is currently EVA-negative. However you will also want to keep in mind what your plans may be with regard to exporting your donkeys/mules/horses to other countries. Vaccinating them may restrict their entry into certain countries.

This summer there has been an outbreak of EVA in a number of states in the USA. In late June there was a large Quarter Horse farm in New Mexico that discovered EVA in its herd. From what I have read, a number of their bred mares were aborting, and after testing, they discovered that one or more of their stallions as well as mares they had bred were coming down with EVA.

According to the Colorado Veterinary Medical Association website, horses that had been on the New Mexico farm were sent to about 23 states before they realized there was an EVA outbreak on their farm. Since then there have been quarantine restrictions in at least 18 states.

As a result, the EVA virus has been circulating here in northern Utah. I was told that originally six mares in Utah were bred to this Quarter Horse stallion with EVA infected semen, and it's just been spreading in our area since then. There are a number of equine facilities in our area that are under quarantine now after horses at these facilities contracted EVA. And just yesterday I read that several more horses had contracted EVA from an infected horse that went to a local show.

This virus can be quite contagious, and once introduced, can sweep through a barn like wildfire. You may want to check with your state veterinarian to find out the EVA status in your state, and also may want to be careful about haul horses/donkeys/mules to sales, shows, and other equine facilities or places that other horses frequent until this outbreak is under control. To protect your herd, new arrivals should be isolated at least three weeks before coming into contact with any other equines, but especially jennets/mares in foal. I am keeping my donkeys at home until this outbreak is over, and hopefully they won't get it!

Please consult your local veterinarian for equine medical advice, if you have any questions about EVA, or suspect your donkey/mule/horse may have been exposed to EVA or sick with the virus. Your State Veterinarian can also provide you with information about any current outbreaks in your area.

Here are also several good website links for more information about EVA:

Kristie Jorgensen

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Posted by Kristie Jorgensen at August 10, 2006 10:00 PM