I have heard (seems reasonable), to not let your dog follow a raccoon into the water because of how comfortable raccoons are in the water such that they can easily drown a pursuing dog. Sometimes a dog will mortally wound a raccoon on land before it gets in the water. Raccoons are fierce and can definitely kill each other. Tough critters! A large dog like a German Shepherd can often easily dispatch even a large raccoon once they they get the knack of it. In my experience, they are just curious initially, but once bit, curiosity turns into a different emotion...