We just got a Jack Russel female dog from the shelter a couple of months ago. She is 5 years old. One of the annoying behaviours she has is to become aggressive all of a sudden and even bite sometimes.

This happen often in relaxed scenarios where she is resting/sleeping next to us on the couch and being pet very gently. After some minutes she might just start showing her teeth and even biting without any particular reason.

She does it more with my girlfriend and she bit only her so far. She does make noise when it happens with me.

I can't understand what happens to her nor how to stop it.

P.S. she likes to pull on ropes and towels and would come ask us to pull it and she seems to enjoy it but we avoid it because she becomes more aggressive. But she doesn't bite at all when she does that. It's clear it's a game for her.

1 Answer 1


First of all, I would have a vet check her over. Sudden biting like that is often not aggression but a reaction to pain!
Also, you should observe closely when exactly she shows these reactions. Things to look out for:
Does it happen while you pet her, or when you start petting her?
If it is the latter, is she resting, or actually asleep?
Does she react to being touched in a certain spot?

It could be a reaction to a touch she is not expecting, or in a spot where she was hurt at some point.

Last question: does she consistently show her teeth in warning first before biting? If yes: heed the warning! You can send her off the couch to some other spot, you can just stop petting, but do NOT ignore a clear warning! Personally, I would send her to whatever you declare to be "her spot" in the room; preferably, that is some spot out of the way, in sight of her family and in the same room, but a place where she can also lay undisturbed by people walking around.
This way, she is not excluded, but left alone, which shoudl be a perfectly fine state of things during some relaxing on the couch time. (Of course, she HAS to learn to let you touch her when you need to, but from your description, that is not a problem anyway!)

If any issues persist, keep observing what triggers her, and perhaps ask a dog-trainer. As she is a shelter-dog, she will have a history of some kind. But as she seems perfectly happy and friendly at other times, I doubt she does have an agression-issue, just one with being touched under certain conditions. Something to work on, but no need for serious worry :).

  • Thanks for your answer. She does hurt in two spots from vaccines and we avoid touching her there. She does it while being pet for a while in a very relaxed way, so my guess is that maybe she gets a bit asleep and regains consciousness to find her self touched. Also she only stayed in the shelter for a couple of weeks. She had an owner before.
    – Moxy
    Mar 29, 2018 at 9:57

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