There’s an odd story originally printed in the Idaho Mountain Express about a police dog named Dax that bit a schnauzer named Max.
(I have written before about a biting police dog from Edgerton, Wisconsin, but that case was about serious injuries the dog inflicted on two people, one of whom was a police officer.)
In Idaho, it was simply dog v. dog, but even then the dog was kept out of service pending retraining.