If a dog chases a raccoon into water deep enough that the dog needs to swim, the raccoon is smart enough to turn on the dog and try to sit on its head to hold it under water so that it drowns. Once the 'coon gets on the dog's head, it is not going to get off unless the dog gets to shallow water where it can stand and shake its head.
Maletrain is right, check the internet. This is a common tactic for raccoons. They also will attack a dogs eyes with their claws. In addition there's rabies, infections, and Coon hound paralysis, all possible from being bitten by a raccoon. Coon hound paralysis occurs when a dog is exposed to a raccoon’s saliva and is the sudden onset of acute inflammation affecting multiple nerves causing dogs to lose voluntary movement of the back legs followed by the front legs and finally death of the dog. Dirty, nasty, vicious animals.
