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Health Canada says it has approved the use of a birth control vaccine to be tested on free-roaming horses in Alberta.
The Alberta government says horse populations in parts of the province have reached “unacceptable” levels. The province considers horse population control necessary to keep them from having too much of an impact on grazing areas for cattle and wildlife.
Contraception is one of the measures outlined in the province’s feral horse management framework, which also lists removal from the wild and putting horses up for adoption as strategies for population control.
The Alberta government received a “research authorization” for the use of contraception vaccine SpayVac-Equid in late August, a Health Canada spokesperson confirmed to CBC News.
“This research authorization allows the product to be studied in feral horses; it does not constitute approval for general use,” the federal agency said in a statement.
WATCH | Does Alberta have too many wild horses?:
The Alberta government says it is “currently reviewing the approval details” related to horse contraception.
“Alberta’s government is continuing to work with stakeholders and advisory committee members to implement management actions in a safe, humane and science-based manner,” the provincial Department of Forestry and Parks wrote in a statement.
“Currently, these actions are limited to continuing data gathering and adoption.”
The province’s latest feral horse survey found 2,072 wild horses in Alberta’s six equine management zones this year — the highest number ever counted — with population levels in the Sundre, Ghost River, Elbow and Clearwater zones “not ecologically sustainable.”
The Alberta government considers the horses stray animals rather than wildlife.
New strategy aims to build on previous attempts
The province and the Wild Horses of Alberta Society launched a contraception pilot project in 2014 to determine how effective it could be for population control.
Through that program, a vaccine called ZonaStat-H — different from the one now being used, but still containing the same active ingredient of porcine zona pellucida — was administered by shooting wild horses with darts.

From 2015 to 2017, 87 mares received an initial dose, 17 received a booster shot, and five received a third dose. Of the 17 vaccinated mares that were actively monitored, only one was confirmed to have given birth.
The project found that contraception was very expensive — an estimated $1,180 per dose — and challenging due to the rough terrain inhabited by the horses, which made it difficult to keep track of horses and administer booster shots.
The province also cited research indicating that between 45 and 84 per cent of the entire female horse population would need to receive birth control for any noticeable population reduction.
Wild horses have long been a presence in Alberta. Many ranchers see them as nuisances and some want them off the land. Wild Horses of Alberta Society, a non-profit organization, is dedicated to saving these animals and finding new homes for them. They’ve joined forces with veterinary students from the University of Calgary to manage their populations.
This time, Wild Horses of Alberta Society president Jack Nichol says the plan is to capture horses, administer the vaccine by hand, and then release them back into the wild, with vaccinated horses marked to help identify them in the future.
“We feel that’s necessary in order to be able to keep horses out there without nobody having to take drastic measures to reduce numbers,” he said.
Nichol said this method has an 85 to 95 per cent success rate, prevents conception for three to four years, and does not alter herd dynamics. SpayVac-Equid also doesn’t require booster shots, which the previous contraceptive did.
“If the mare happens to be pregnant when they get the shot, it doesn’t change anything,” he said.
Nichol said the goal is to launch the contraception project this fall as part of a new population control strategy, which will also include capturing a limited number of young stallions and removing them from the wild.
“They never want the horses off the land,” Nichol said of the provincial government. “They just want to be able to control the animals, the numbers, as much as they can, to try to keep all the land users happy. Pretty hard to do to make everybody happy, but they are making an attempt.”
The Wild Horses of Alberta Society currently rescues and rehabilitates horses, including those that wander onto private property, and puts them up for adoption. Nichol said the society has taken in more than 200 horses since launching in 2002.


