Page 59 - 2020 Stallion Register

gestation often will abort, and this usually occurs 10-30 days after viral exposure. These abortions do not occur because of fetal infection, but rather from premature placental separation and fetal death secondary to vasulitis in the uterus.
Another extremely important clinical condition associated with EAV is fatal interstitial pneumonia in foals. Infected foals are often born to seronegative (non-infected) mares, indicating the foal is not infected in-utero, but becomes exposed after birth with devastating consequences. Even with prompt and aggressive intervention, most foals will die because of
the degree of lung damage that has occurred. These foals should be isolated as they shed large amounts of virus and can serve as a source of infection to other foals or mares.
There is no treatment for EVA regardless of
the sex of horse infected. Happily, though, EVA is completely preventable. The first step in controlling the disease is identification of carrier stallions. This critical step in prevention can be done definitively through laboratory testing. Stallions are screened for exposure to the virus (antibodies) with a blood test and if they present with a titer of greater than 1:4 then a semen evaluation is performed to identify viral shedding. Infected mares and foals can be positively identified by the presence of antibodies in nasopharyngeal or vaginal swabs or blood tests; and the virus itself is identified in abortion situations.
There is a modified-live virus vaccine available in the United States (ARVAC) which is required to be given to breeding stallions in New Mexico at least 3-4 weeks prior to the start of the breeding season. Stallions must have a negative
EVA can be transmitted 2 ways: Aerosol-inhaled viral particles transmitted through infective nasal secretions or urine and Venereal. Mares infected via the venereal route may not display clinical symptoms, but will shed large amounts of the virus from nasal secretions and urine, leading to lateral infections through the aerosol route of transmission.
blood test and/or negative semen test PRIOR to administration of the vaccine. This vaccine must be administered by a veterinarian and requested by your vet through the State Veterinarian in
New Mexico. This vaccination protocol prevents the creation of a carrier stallion situation and ensures that the mare population is protected. It also effectively stops the aforementioned lateral shedding that occurs after a mare is exposed via the venereal route. It is imperative that vaccinated horses remain isolated from seronegative horses for 21 days after vaccination, as viral shedding
can occur. Mares who are to be bred to carrier stallions should be vaccinated at least 3 weeks prior to exposure to the stallion/semen and should be vaccinated annually. The vaccine should not be given to pregnant mares or foals under 6 months of age. Proof of a negative test and subsequent annual vaccination is required in New Mexico for a stallion to be registered into the New Mexico breeding program. If proof of process cannot
be supplied, the stallion must go through the testing (blood and semen) protocol, as antibodies from vaccination cannot be distinguished from a natural infection in the blood test.
While Equine Viral Arteritis can be a devastating and frustrating disease condition, implementation of good management practices can lead to prevention and control of the disease should it arise. Isolation of all new arrivals for 3-4 weeks, segregation of pregnant mares from the general horse population, and testing and vaccinating all breeding stallions are simple and cost effective ways to reduce the risk of exposure and potential huge economic losses long-term.
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The symptoms commonly seen with EVA include fever; edema of the lower limbs, scrotum, udder, or ventral midline; conjunctivitis and tearing; skin lesions; inflammation of the nasal passages and nasal discharge.
While Equine Viral Arteritis can be
a devastating
and frustrating disease condition, implementation of good management practices can lead to prevention and control of the disease should it arise.