Equine herpesvirus-1 (EHV-1) has been in the headlines lately as outbreaks have occurred across the country. EHV-1 can cause respiratory infections as well as neurologic disease; it can also cause abortion in pregnant mares.
The virus can be difficult to control; adding to the difficulty of curbing the disease, horses can shed the EHV-1 without showing any outward signs and without the virus showing up in blood tests. Horses that look healthy can spread the disease through nasal discharge and through an aborted placenta and fluids. It has now been determined that mares are able to shed the virus from their vagina, as well, reports The Horse.
Dr. Carina Cooper, DVM, with the University of Guelph's Ontario Veterinary College in Canada, presented her findings on EHV-1 at the 2018 American Association of Equine Practitioners Convention. Cooper wanted to determine how prevalent EHV-1 was in healthy broodmares and if vaccinating them during pregnancy was effective.
Cooper used 385 healthy broodmares of varying breeds on 45 farms in Canada. She collected blood samples, nasal swabs and vaginal swabs ever two moths during the breeding season. She was able to determine that 85 percent of the mares had EHV-1 at least once during her study; 65 percent of mares shed from their vagina (55 percent) or their nose (33 percent).
Cooper also discovered that the mares had lower levels of the virus in their blood later in pregnancy. Though this is counterintuitive, she notes that no correlations can be drawn just yet. Cooper also said that vaccination is most likely not very helpful in preventing mares from becoming latent carriers of the disease. While the vaccine may reduce the prevalence of the virus in the blood, she doesn't feel that it reduced the amount of the disease that was shed by the mares.
Cooper noted that a herpesvirus never truly leaves a horse's system; they horse is infected for life. The most important thing horse owners and caretakers can do is use proper protocols and isolation to prevent the spread of disease. Cooper calls for further research on the vagina as a source of infection or ability to spread disease.
Read more at The Horse.
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