Equine Herpes Virus - You Oughta' Know About EHV-1

"In Saskatchewan in March /April 2011, Prairie Diagnostic Services reported three cases of EHV-1. In 2010, there were three positive cases detected in Saskatchewan. There has not been a demonstrable increase in illness due to EHV-1 in Saskatchewan in 2011.

"We caution against mass hysteria in response to the many reports of EHV-1 that are circulating in our province and in Alberta as well. Alberta has, to date, only one confirmed case of EHV-1 with neurological signs, that being a horse that was at the National Cutting Horse Show in Utah at the end of April/beginning of May. Several additional cases have been reported in Idaho and Colorado.

"We also continue to caution all horse owners to always observe strict biosecurity protocols when handling their horses either at home, in the barn, at outside pastures and stables, on the trail, or when participating in clinics and competitions in the company of other outsider horses. One can never be too careful. At the first signs of any respiratory disease in a horse it should be isolated and strict antisepsis measures followed in its care and handling.

"As the summer season advances so too does the opportunity for the spread of many forms of equine illnesses.

"The Saskatchewan Horse Federation will continue to advise its members of any changes in the current situation surrounding concerns of possible outbreaks of the EHV-1 virus."

~ Mae Smith - Executive Director

This is not an outbreak limited to cutting horses.

While one outbreak appears to have presented at the Ogden, Utah show, there is some information that at least one of the infected horses had already attended or passed through several Canadian equine venues. It is possible the virus was present in Alberta and possibly Saskatchewan before the Ogden show. Please remember, this is not confirmed. The point is, cross-contamination is certainly possible. Consider not only where your horses have been for the past 20 days, but also, who has been in contact with them, whether at an event, or at home.

The best preventative is common sense bio-security.

The virus is transmitted via direct and indirect contact, and to a lesser degree, through the air. Transmitting, or "shedding" the virus through respiratory channels is the most common, and generally lasts for seven to 10 days, but it can persist longer. If your horse has been in a high-risk situation, a 28 day isolation period is recommended by the American Association of Equine Practitioners.

(If your horse was present at the Ogden, Utah show, you should let your veterinarian know. And remember, while the disease is not reportable federally, it is in some provinces, such as Alberta.)

Don't underestimate the power of indirect transmission such as nasal secretions left on equipment, tack, feed and other surfaces. The AAEP suggests it is "an important route of transmission of the virus. Indirect transmission occurs when infectious materials (nasal secretions, fluids from abortions etc.) are moved between infected and un-infected horses by people or fomites (inanimate objects).

Poor hygiene (such as lack of handwashing) and sharing of equipment are often responsible. People who have touched or otherwise come in contact with infected horses should change their clothes and thoroughly clean and disinfect their hands before handling other horses."

Whatever event you're planning on attending with your horses over the coming weeks keep in mind it has been suggested the virus can survive for up to 35 days, but only if it is an ideal environment.

Some trainer facilities, particularly those which had horses in Ogden have voluntarily imposed isolations on their own facility - no incoming/outgoing horses, no lessons - as a preventative measure. Considering the contagious nature of the virus, this is a pro-active course we should all appreciate.

What is the primary symptom?

Often preceding other signs is the presence of a fever. If you are concerned be sure to take your horse's temperature twice a day. This is easily done with a rectal thermometer. If you need a refresher on how to do this, read here. The temperature of a normal horse is below 38.5°C (or 101.5°F). According to Moore Equine Veterinary Center, "It is best if you can keep a record of the rectal temperature trends in your horse. Most infected horses will only show mild respiratory signs including coughing and nasal discharge. Early signs of the neurological form of herpesvirus usually involve incoordination of the hind limbs, urine dribbling or being unable to urinate."

Is there a vaccine?

While there are several vaccines against EHV available, none of them state any protection against the neurological form of EHV infection. Check with your veterinarian to determine the validity of booster vaccinations in your animal's case.

We touched base with Ashley Whitehead at the University of Calgary Faculty of Veterinary Medicine to ask her some questions about the virus and what we can do to help prevent its prevalence in our midst.