I'm really worried for my roommate's dog. He's a Chihuahua (Other people and I agree he's a Chihuahua/Rat Terrier mix, but my roommate stubbornly refuses to agree because "that's not what they said on his papers" from the pet store) named Pablo, and she got him when she works a job at a restaurant every day, and a lot of times she works double shifts and/or gets off work but doesn't come home for hours, leaving him here alone for either myself or my boyfriend to take care of (she doesn't ask us to but I personally feel so horrible for the poor guy to be all alone in a room for hours on end). Ignoring all these things that are a blinding reason as to why she NEVER should've gotten a dog in the first place (we don't even bother bringing up the subject anymore because she gets mad and tells us "not to tell her what to do" and "it's HER dog, butt out", basically. She even told my boyfriend that I had no idea what I was talking about when it came to dogs, even after knowing I've trained dogs before. Basic training but still) we can't change the fact that she has him and that he's rarely socialized. Pablo sees only 3 people on the regular and maybe 4 people outside of that occasionally. We live in an apartment building and there are kids running around all the time. They always want to "pet the puppy", and at first I would let them. But I noticed the hair on his butt standing up, and before I could do anything, he snapped at the kid! And it's happened more than once, and when my roommate has had him out as well. He even snapped at my co-worker when she gave me a ride home, he was totally fine with her then all of a sudden if she reached to pet him he'd go for her hand. She tried at least 3 times to pet him with the same result before she just gave up. My first sign is he flinches if someone reaches for him, his ears kinda pull back (he doesn't show his teeth, he just looks "nervous") and his hair starts to stand up. Sometimes he'll growl, sometimes he won't. He also thinks every toy/bone/food is "his" even if it's not, and will growl and sometimes even attack if another animal tries to take or get near them. He's gone after my boyfriend's parent's Chihuahua before, and he attacked our kitten for playing with one of his toys just the other day. (Rascal gave it right back to him though, Pablo went yelping and running, but Rascal has a cut on his forehead now that's missing hair. No blood though.)

I'm really thinking he has fear aggression/aggression issues, but I know even if I tell my roommate she'll blow it off because it's her "baby" and he can never do wrong. Or if he does, she scolds him then IMMEDIATELY cuddles him and pampers him, which completely negates the scolding in the first place. What can I do to help Pablo? I don't want him to bite someone and there be a huge lawsuit and him get taken away or put down because of his owner who doesn't think there's a problem. And how can I show her that something is wrong? If I can prove it then there's a MUCH better chance she'll not go "You don't know what you're talking about".