Q:  I have a foster rescue with a growling issue that I would like to understand. She is a small terrier, and quite dominant with other dogs. She is very well trained, and will roll on her back when given a down command, as well as whenever I bend over her (like when putting on her leash). She is obedient, submissive and affectionate with me. However! whenever I pick her up, or just pet her she constantly growls, and will even occasionally show her teeth, or put her mouth on me. The minute I withhold the petting, and say "no growl" she stops, and then tries to get me to pet her again. If I do, she goes back to growling. Can you give me an idea of what may be behind this behavior?

A:  Props to you for fostering!

The behavior you describe is complicated. An interesting clue is that your foster rolls onto her back in response to the down cue and when being leashed. It's true that rolling on the back is generally a deferential or submissive signal, and it's also food for thought that your foster responds this way to a cue and to being bent over. It suggests some discomfort in these contexts. Indeed, the behavior expert Sarah Kalnajs points out that rolling onto the back can often be read as a "please stop" signal.

Consider this in combination with the constant growling plus tooth-baring and putting her mouth on you when you pet her.  She's quite uneasy with handling! Stopping may actually reward her growls.

At the same time, you point out that when you stop petting her, she'll solicit petting again. She might just want attention (but not petting), or she may really feel ambivalent, wanting you to pet her but then becoming anxious as soon as you begin.

That's a surprisingly common phenomenon among dogs. For instance, a colleague of mine has a dog who will approach other dogs with friendly tail wags and a so-called "submissive grin," but who will then snap at them almost as soon as the greeting starts. She has a social interest in other dogs, but is profoundly uneasy with them close up.