Why would my dog suddenly try to attack another dog when he has never done that before?

Question

We were at Petco with our dogs (6.5 mth olds Pepper-cockapoo, and Bandit-lab/pit mix) walking around enjoying ourselves when we go to turn down an isle and there is a man with a full blooded brindle pit bull and a smaller baby pit bull in a buggy. The man's pit bull sees and and tries to head down the isle towards us. He wasn't growling or barking or anything. He was just pulling his master trying to get down the isle.

Bandit (lab/pit mix) suddenly puts the hair up on his back and starts growling and showing his teeth. He was very agressive and he isn't like that. We have been to Petco before with him. He takes training there every Tuesday. There is even an agressive Rotweiller in our class and he isn't even that way with him. He has been around other dogs outside of Petco. We have an older pit bull down the road, 2 austrailian shepherds, and a border collie, and he has never been agressive with any of them.

He has been food agressive at home, but only with Pepper, never us. But then he and Pepper will share the same water bowl at the same time and he doesn't have any problem with that.

We immediately pulled him away from the situation and scolded him. I have never seen him act that way to another dog. So does anyone have any ideas what could have been going through his little (well, not so little since he does weigh 45 lbs) mind when that happened? I would appreciate any help or suggestions.

Answer 1

I don't own a dog right now but have in years past. My first reaction is

that he saw this dog as a threat to you and was putting on a defensive position to scare this dog away from you. It is difficult to tell without

being there and seeing the dogs body language. But it definitely sounds like he saw this dog as a threat to you or him and was going to fight to protect you. The fact that he has been around other dogs

and never shown this side means to me that none of these other dogs

ever showed any sign of 'going' for you. just the usual  friendly stuff. Something was definitely up that day!

Answer 2

He was probably trying to protect you.