What does it mean when my dog backs his butt into me while sitting?

It could be a way of Tally showing you affection. She feels very bonded to you, and she always wants to be touching you in some way. Dogs greet each other by sniffing each other's behinds, so it could be her way of putting her scent on you. Dogs show love to humans in their own way, and Tally more than likely wants to always touch you in some way, even with her butt :-)

Pets can do some really odd play behavior sometimes or she may have wanted her rump scratched. Growls can be used to indicate aggression, play or if she has learned that the sound gets her owner's attention (she will then use this sound when she wants the attention). You must look at the over all body language (head position, tail position, where is she looking, are the legs stiff...etc), to know the true meaning. I hope this is helpful and please feel free to post any additional questions.

Hello, this is likely Sirius releasing his pheromones on you in a way to show affection. This is a natural instinct and typically does not mean anything other than him showing you affection. Hope this helps and best of luck.

Dogs will often sniff each other's rears in an attempt to gain valuable (to them) information about each other. Your dog may be doing this to you out of curiosity of what you're like! If he is being too rude it is best to simply get up and stop giving him attention. He'll quickly learn the behavior doesn't get him anywhere, while sitting nicely or performing other behaviors gets him attention!

This is normal. Sometimes it's hard for dogs to reach that back area, so when it's scratched, they get a lot of pleasure from it. Cats can behave the same way when you scratch that area as well. It's not sexual. I hope this helps!

It might mean that the Chihuahua has an unusual or interesting odor in this area, which could be due to an anal gland infection, vaginal infection, or active heat cycle. It could also just be your dog's way of being friendly, although this kind of interaction is often seen as "rude" by other dogs.

Without a complete history, it is near impossible to determine what may have happened to make Booboo respond in this way. It could have been a past traumatic experience or it may simply be old age changes. Since you know he is uncomfortable, try to prevent other dogs from approaching him in this manner in the future.