My dog randomly shows 'tail aggression' towards himself. It has happened with resource guarding a large treat, but never when he's eating something small. He also does it at night when hes sleeping. I think he is trying to get at his butt where his tail meets his body. What could this be?

Is it just towards his tail or does it almost appear as if he doesn't realize his back end is attached to his front end?  We had a dog come into the shelter like that and when someone would touch his back legs or various areas on the back end of his body (tail included) he would try to attack himself. Our vet said it's essentially the animal has a neurological problem that does not allow him/her to recognize it as a part of himself and is a type of body dysmorphia. To her knowledge there isn't any treatment and they can injure themselves or someone around them. It was really unusual to watch him as it wasn't typically what dogs do when they are trying to use their teeth to scratch at an area (like the base of their tail), he genuinely would try to attack himself and would spin around in circles trying to do so growling and snapping the whole time.

@Sheila DVM - I'm blanking on the dog's name you worked with who had a similar issue.  Any advice?

sweet Finn!