Why would a dog that has never shown aggression get overly aggressive with a puppy?
I have a two year old neutered male Cardigan Corgi that has never shown any aggression to dogs or people. He was well socialized as a pup and I take him lots of places, including a dog park. He's been the beloved star of the dog park -- until today. Not only has he never shown aggression at the park, he's only rarely "talked back" to other dogs getting too rough with him.
He does get very wound up to go the park, primary to chase tennis balls. (He is now much more excited about the opportunity to play ball than play with other dogs.) Today for some reason he got aggressive with a four month old golden retriever pup to the point of breaking skin. It started with playing that escalated to dominating whenever she got too close to him and ended when he drove her off with some bites to the top of her head, enough to produce specks of blood. He stopped when I yelled and came when called. It really felt like his frenzy over playing ball boiled over, but I've never seen him act like that before, although he does seem to be getting more and more protective of the ball.
Any insights? He is such a reliably good natured guy -- this has just thrown me for a loop and I'm reluctant to take him anywhere until I better understand what's going on. I will be taking him to the vet this week to be checked over.
Moat aggressive dogs in my experience give puppies a pass, meaning they wont hurt them as they are not a threat. guess is things just got a little too out of hand just like when ppl have conflicts. I wouldnt be concerned the puppy is just being put in its place. Your corgi is too small to hurt bad.