An Acton farm is dealing with quarantined horses, extra sanitization and daily doses of medicine following an outbreak of a deadly horse virus.

Vanbrook Equestrian Centre is now closed to the public while they handle the virus.

"It is a hardship, because I still have to pay for all these horses and they still need to eat and be cared for with no income coming in," owner Julie Van Wieren said.

The virus, called Equine Herpes Virus One or EHV-1, killed three horses at the farm. Twenty-two of the 86 horses at the property have now tested positive. Every horse has been tested twice.

"It's been really hard and it's hard going around and not knowing if there's going to be another one that gets sick," farm manager Brittany Simmons said.

Typically, there are one to four cases reported each year in Ontario. However, an increase in cases has prompted a warning from Van Wieren to other farm owners in the area.

"Over 70 per cent of horses in North America are exposed and carry this dormant in them," she said.

Veterinarians said EHV-1 can't infect other animals or humans, but symptoms can worsen quickly in horses.

"They show fever and they can have swollen legs, they get very puffy legs," said Luis Arroyo Castro with the Ontario Veterinary College.

The Ministry of Agriculture said two other farms are dealing with outbreaks. One is in Niagara and the other in Peel.

"We don't have any epidemiological links between these three farms," said Alison Moore, lead veterinarian with the ministry.

Moore said they don't know how the outbreaks started.

"It could have been the stress of the cold, and recently we've had a really cold snap of weather," she said.

Horses can spread the virus through nose-to-nose contact.

Van Wieren said barns should quarantine any new horses.

"It was really sad," she said. "They're part of our family. They've been with us for years and years.

Barn staff are working with the University of California to help them study the virus.