14/ MAY 2018 THE RIDER Research targets equine virus


Story and photo by: Karen Man- tel


Guelph, ON April, 11, 2018 - Re- searchers at the University of Guelph are searching for clues to better manage a virus that can cause late gestation abortion in mares. Horses carrying equine her-


pesvirus (EHV) may exhibit signs as minor as a runny nose and mild fever, but the virus is a major cause of neurological, res- piratory and reproductive dis- ease, including abortions, in the equine industry. Horses often are infected


early in life and EHV can remain in the body for life, reactivating at any time, but it’s not clear what causes this to happen. Something pushes it over the edge to disease manifestation, explains Dr. Bran- don Lillie, a pathologist in the Department of Pathobiology at the University of Guelph’s On- tario Veterinary College (OVC). While vaccination is recom-


clinician and researcher


mended to protect against EHV, the virus continues to occur in vaccinated herds. Affected horses may abort their foals or foals may be born apparently healthy only to die a short time later. Lillie and Dr. Luis Arroyo, a in


OVC’s Department of Clinical Studies, along with their research team are trying to better under- stand how the virus exists in the horse population, uncover what triggers the virus to cause disease and assess ways to maximize cur- rent EHV vaccination efficacy and minimize the virus’s effect on the horses’ health. In particu- lar, they are focusing on the abortive affect of the virus. EHV can present in a num-


ber of ways, explains Arroyo. Horses may demonstrate neuro- logical signs; they may have dif- ficulty walking, they may have difficulty urinating because the nerves to their bladder are in- flamed, or they may exhibit milder symptoms like a runny nose, or no symptoms at all. A mare may not show clini-


cal signs of the virus at all, but could lose a foal who is loaded with the virus, he adds. Con- versely, some mares may be clearly diseased but their preg- nancy isn’t compromised. The cyclical nature of the


virus is part of the challenge. Farms may report no abortions for a couple of years and then suddenly they have two or three. The researchers began with


a survey of Ontario horse farms to better understand the current


2016,


state of the industry, looking at herd sizes, abortion rates and prevalence of EHV-related dis- eases. Beginning in December they began sampling


horses on farms across Ontario – from Ottawa to Windsor and Sudbury to the Niagara Region. The farms include large rac-


ing operations with dozens of mares to smaller farms with two, three or six mares. Says Lillie, “We are focusing on the mares because that is the major way that foals get infected. We think that’s an important area to look at and understand.” Horses on each farm will be


sampled six times over 12 months, essentially covering the entire gestational cycle of horses. Lillie and Arroyo are also


examining the best way to sam- ple for the virus, looking at nasal swabs, vaginal swabs and blood samples. “If a mare is shedding are


there different levels in different places, are you better to swab a horse’s nose or to take a blood sample?” asks Lillie. They will test the samples


for presence of the virus or viral DNA levels and also look at serology, the mare’s antibody level or immune response to the


virus. Using this information, re- searchers can then determine how prevalent the virus is, the impact of vaccines on the virus and the mare’s ability to mount an immune response. On the farms being studied,


there is also a fairly even split be- tween those who vaccinate and those who don’t. “Hopefully we’ll start to see


some trends,” adds Lillie. “Ulti- mately, when abortions occur, we can look back and see if the shed- ding pattern changed and if one type of sampling was a key indi- cator.” Another area they will as-


sess is how the antibody response pattern changes with horses throughout the year. Preliminary evidence suggests not all mares respond the same way to the virus or have the same antibody level patterns over the year. The host, the pathogen, the


farm’s management strategy and the environment all contribute to the occurrence of disease partic- ularly when a virus is there all the time, adds Lillie. Ultimately, the researchers


hope to make some changes in how the disease is diagnosed and managed. “Maybe vaccine proto- cols need tweaking,” he says. “Maybe the current vaccination


Dr. Brandon Lillie, a pathologist in the Department of Pathobiol- ogy at the University of Guelph’s Ontario Veterinary College


(OVC) and Dr. Luis Arroyo, a clinician and researcher in OVC’s Department of Clinical Studies. Photo Credit: Karen Mantel


schedule isn’t the best as far as timing or maybe another one is needed in there, or perhaps the virus has evolved a bit.” Funding for the study has


come from the Ontario Ministry of Agriculture, Food and Rural Affairs and a University of Guelph Catalyst Grant, as well as funding from Equine Guelph and the Zoetis Investment in Innova- tion Fund.


About Equine Guelph: Equine Guelph is the horse own- ers’ and care givers’ Centre at the University of Guelph in Canada. It is a unique partnership dedi- cated to the health and well-being of horses, supported and over- seen by equine industry groups. Equine Guelph is the epicentre for academia, industry and gov- ernment - for the good of the equine industry as a whole. For further


information, www.equineguelph.ca. visit


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