With four horses dead in little more than 24 hours at the Calgary Stampede, organizers decided that due to safety concerns they would cancel the nightly chuckwagon race.

"The safety of our patrons, participants and animals is our first priority," said Paul Rosenberg, the Calgary Stampede's vice-president of programming. "With the weather forecast calling for even more rain and wind, we feel it's imperative to cancel the chuckwagon races and the Grandstand Show."

The chuckwagon race track was already muddied by a day of rain, and forecasters were calling for an additional 10 millimetres of rain and strong winds for Tuesday evening.

Several animals have died at the stampede in recent days. The latest horse death occurred late Monday, when the animal broke its shoulder competing in the chuckwagon event.

Veterinarians treated the horse immediately, but decided its injuries were so severe, it needed to be put down.

Earlier on Monday, a horse died during the novice saddle bronc event, when it broke its back after bucking its rider off.

Another horse died of a heart attack Monday, as it trained for a chuckwagon run.

And on Sunday, a horse died instantly of a heart attack during the team cattle penning competition.

In that case the female rider, Amy Carver, sustained a traumatic head injury when she was pinned under the horse as it fell to the ground. Carver is still in intensive care.

The spate of deaths has led to a barrage of criticism from animal rights' groups.

Desiree Arsenault of the Calgary Humane Society said the society needs raise its voice to ask the Stampede to remove "high-risk" events such as chuckwagon races.

"It's just a matter of looking at the use of animals in the entertainment industry and deciding whether that's something society wants to continue," she told CTV Calgary.

The Vancouver Society and the U.K.-based group, League Against Cruel Sports, have been outspoken in their criticism of the Stampede throughout the last week.

Doug Fraser, a spokesperson for the Stampede, said event officials were "upset" by the deaths and by Carver's injury, but maintained that the rodeo's practices were sound.

"We know some people have different views about animals and we respect their right to hold those opinions," he said. "But we trust that they will respect the opinions of the millions of Calgarians, Canadians and international visitors who admire and respect the Calgary Stampede."

Four animals -- one steer and three horses -- died last year at the Stampede.

With files from The Canadian Press