I think it's in black and white, but not too sure. Watched it in 1998.
It's 2-3 bank robber, one of them tried to pull the pin of a grenade using his teeth, causing his pantyhose mask to tear and reveal his face.
Then there was a scene where one of them was injured, so they brought him to the only doctor they knew, a vet, who treated him like a dog/pet, putting a bowl of water on the floor for him to drink.
Help anyone? Can't get it out of my head! Thanks all...

I think the movie your looking for is Three Fugitives with Nick Nolte and Martin Short