Sterling Downey, Projet Montréal's spokesperson for wildlife management, says if it's too hot outside for humans, then it's too hot for the horses who pull carriages through Old Montreal.
"The city needs to be more vigilant and proactive in enforcing rules for this industry," Downey said Thursday.
"We need to review these bylaws, these rules governing the industry, and make sure that the animals are protected."
As it stands, Montreal caleche horses aren't allowed to be working if the temperature recorded at Trudeau airport by Environment Canada is above 30 degrees.
On Wednesday, outraged Montrealers posted photos on social media after spotting horses working during the recent heat wave, which prompted a warning from Environment Canada.
Some say the horses are being forced to work in inhumane conditions.
But the temperature didn't hit 30 until 3 p.m., meaning caleche drivers were not breaking the rules.
Still, Projet Montréal says the city should be more strict.
The party is asking the city's executive committee to intervene and order drivers to take their horses home whenever there is a severe heat warning in effect.
"The executive committee needs to move on this immediately, modify the bylaws, make sure they take into consideration all of these concerns," Downey said.