Clnire, do you have a minute for dog advice? Our two 4 year old chihuahuas are litter mates, and have always gotten along very nicely. Over the past two weeks, one of the dogs periodically attacks the other -- baring teeth, then growl, then pounce! Neither is sick (they were at the vets three weeks ago). This seems to happen when I have both dogs sitting with me. I'm wondering if the attacker is "worried" that his brother is going to get more attention ... Any ideas and/or suggestions? (Thank Heaven for the back porch!)
My first suggestion would be vet check but sounds like you have that covered. I would then agree it could be jealousy. They do get jealous, not matter what anyone says!
What to do? Hard call. Mainly make sure you supervise. Do you have crates or a way to confine the attacker? Sometimes a time out in a crate can help. Otherwise to make sure when the attacker is being good to give it lots of attention. Hard management issue, you will have to be aware at all times and try to interrupt before an atrack happens.
Watch the attacker's body language. They move fast but if you can notice a .... of the ear, a look in the eye, a hunch of the back, distract! Call him, throw a toy, something to break the build up of aggression. If you are observant you will recognize signs.
Spock was attacked by a Rottweiler as a 6 mo old puppy and lived the rest of his life with the motto "I will get you before you get me". With close management and observation, he went on to be a multi mega titled performance dog. But it was not easy! Tasha is a girl because I would not have wanted the challenge of him with another male. Tasha was fine, besides, 2x a year she smelled real good (Spock was neutered but he didn't care!).
Finally, don't get mad! Agression feeds on aggression. A firm "no!" is fine, a firm pick up and remove from the area, fine. But anger will only add to the situation.
Hope this helps. If I think of more things I will let you know.
There ends the dog training lesson for now