The initiative follows the firing of employee Carla Cheney in Kemptville, Ont., who claims she was let go after confronting a customer who had left his dog in a car amid sweltering temperatures.
A statement from Wal-Mart says Cheney wasn't fired for trying to help a dog in a car, but didn't offer any further explanation due to "privacy reasons."
Cheney's lawyer Robert Monti says his client doesn't accept that and will bring a wrongful-dismissal suit against the mega-chain.
Wal-Mart says it has a long-standing protocol that tells employees to notify authorities if an animal is in distress or at risk.
The Kemptville incident followed the death of a dog who had been left in a car parked at the Vaughan Mills shopping centre north of Toronto in June.
Authorities also issued warnings not to leave children unattended in vehicles after a boy in Milton, Ont., and a girl in Edmonton died this summer after being left in hot cars for extended periods of time.