Provincial police in Alliston are reminding residents not to leave their dogs in cars after receiving 18 calls reporting such incidents so far this summer.

They say they've spoken with a veterinarian, who told police that when animals are left in vehicles it can turn deadly fast.

Police say the vet told them that an animal that's left in a vehicle for just 10 minutes when it's 20 degrees Celsius outside can experience brain swelling or heat stroke.

Officers are asking anyone who sees an animal in distress in a vehicle to call 911.

They're also asking people to leave their pets at home on warm, sunny days.