Protesters chained themselves to the gate surrounding the race track, putting the event on hold for about half an hour. In a statement, the Vancouver Animal Defence League says they hoped their efforts would prevent "the cruel chuckwagon bloodsport" from happening
"They chained themselves to the track and they wouldn't move," said Murray Clark, who witnessed the protest. "[They] couldn't get the chains undone, I don't know where they got the keys from, so they got some cutters over there, covered them over and they were were over there for awhile cutting. It took half an hour to get them out of there."
The two women were ultimately cut free and arrested.
There's no word on any charges yet.
It's not the first time the chuckwagon races have been the subject of protests.
Last year, Mötley Crüe drummer Tommy Lee urged former Alberta premier Alison Redford to cancel the races, calling them a "bloody spectacle."
In chuckwagon races, teams of horses compete to pull wagons around the track the fasted.
They are the deadliest Stampede event for horses, with more than 50 horses dead over the past 20 years.
In 2012, three horses died in a chuckwagon crash after the lead horse had an aneurysm and pulled down three other horses and an outrider.
However, the Stampede has tightened the rules around chuckwagon racing in recent years in an effort to make the event less dangerous.
In 2011, new rules regarding mandatory rest days, vet checks and limits on the number of outriders used brought the Stampede's Rangeland Derby in line with the World Professional Chuckwagon Association and the Canadian Professional Chuckwagon Association.
Those rules also brought in changes for several other Stampede events, including tie-down roping and steer wrestling.
"We fully understand that what is acceptable to the majority may be unacceptable to some," said Bonnie Clark, the Calgary Stampede's spokesperson. "I can tell you that we understand some people will never agree with the use of animals in production, or in competition or as athletes."