Fatal horse disease rears its head in Manitoba

Equine infectious anemia has been found in Manitoba for the first time since 2006 and 14 horses have been euthanized in the province so far this year, according to a veterinarian with the Canadian Food Inspection Agency.

The province has seen 14 cases of equine infectious anemia this year

Equine infectious anemia has been found in the province for the first time since 2006. (Tina Lovgreen/CBC)

It's a horse disease that's always fatal, but it isn't always immediately apparent your horse is sick with it.

Equine infectious anemia has been found in Manitoba for the first time since 2006 and 14 horses have been euthanized in the province so far this year, according to a veterinarian with the Canadian Food Inspection Agency.

The disease, sometimes called "swamp fever," is eventually fatal, said the CFIA's Dr. Alex McIsaac. It starts with intermittent fever, then progresses to jaundice, swelling underneath the horse's abdomen and on its legs, and tiny hemmorhaging in its eyes. 

"Eventually, the horse is hanging its head down, is unable to breathe and eventually will die," said McIsaac.

There is no human health risk from the disease, according to the food inspection agency.

There have been 14 cases found on six farms in Manitoba in 2017, said McIsaac, including in the rural municipalities of Armstrong, St. Clements, St. Andrews and Hanover. All six farms were put under quarantine but two of those quarantines have since been lifted. All 14 affected horses were put down to prevent suffering.

No treatment for disease

Equine infectious anemia is a viral disease transmitted by biting insects, mostly flies. From there, it can be transmitted from horse to horse and throughout a herd, said McIsaac. 

He said while the disease has been reported in Manitoba horses this year for the first time since 2006, it was likely always here. 

"I'm not sure it's a problem that's arisen this year. What it is, increased surveillance has found it this year," he said.

"Most animals that are affected with this are — by far the majority — are what we call inapparent carriers. So they have the virus in their system, but outwardly, unless you really, really know the horse, you wouldn't think that they're infected."

Prevention and treatment also present challenges, he said.

"There is no vaccine, which is unfortunate. There is no treatment as well, which is also unfortunate. So for the rest of the life of that horse, it would remain as a reservoir of disease for all other horses around it," McIsaac said.

"It is a difficult diagnosis to get."

Testing voluntary, but important: veterinarian

Testing for the disease is voluntary in Canada and generally only done when a horse is being moved for a show or to another farm. "That's the only time that you would discover that you had the disease," McIsaac said.

Saskatchewan has seen more than 100 cases of the disease over the past few years. When an infected horse is found, it is quarantined and the entire herd is tested.

"So it might sound simple that yes, you might find a positive horse, that horse is euthanized and those other horses should be released. However, that horse may have infected its herdmates in the meantime," McIsaac said.

Owners have to wait 45 days to see if their herd has been infected before the quarantine can be lifted. 

Manitoba's cases were discovered when a breeding farm asked to have a new horse tested. "Once you make that initial discovery, the word gets out … then people ramp up testing," said McIsaac.

"I think next year, a lot more shows and events will have their horses tested prior to entry. In Saskatchewan, two years in a row we had an increase in numbers simply because we started looking more. Next year, that's likely to be what might happen [in Manitoba]."

Still, horse owners shouldn't panic, the veterinarian said.

"This is not like a wildfire disease that spreads really, really quickly. But I do think it's important that you test, and I do think it's really important that you test any animals that are new to your property."