Good question, but she's been spayed for over a year now. Not sure if it's worth mentioning or not, but because she is part shiba, she does have a soft undercoat that she's completely shedding right now. She blows it about twice a year. I'm not sure if that can cause some irritability.

I believe her wellness check was back in October. It has been recent, but I'm feeling like I need to call them again to explain this sudden behavior.

She's always been a little snippy at most female dogs, but some in my neighborhood she's friends with. Recently at the dog park, it's hard to tell exactly what sex they are when they come up to her, but it's been every dog she's had a problem with (besides the rat terrier).
Last summer (before my sister's dog came into the picture) at the dog park she was very playful and I never had any worry she'd start something with another dog.

When I walk both dogs together, she's interested in the other dog, but as soon as she smells for a minute, then she immediately starts snarling and going for their throat. When I walked her alone, for the most part she'd be friendly enough. I do wonder too if the rat terrier's barking is making her feel protective.

She turned two in November

My basenji/shiba inu mix has started all of a sudden showing aggression toward other dogs.

Last summer I took her to the dog park regularly and she was very good with other dogs and wanting to play aside from the occasional nips. This summer when I started taking her back to the dog park she has started fights with any dog that shows interest in her.

The only change in her environment has been my sister moved in with her dog (rat terrier) and they get along wonderfully. But whenever I take them both for a walk, the rat terrier barks (non-aggressively) to any person or dog he sees and my dog growls, snaps and goes for the other dog?s neck. My dog shows no signs of aggression toward people at all, only other dogs.

Should I continue taking her to the dog park to re-socialize her? Perhaps without my sister?s dog? This new sudden aggression to other dogs has been very concerning.

I appreciate any insight you could provide!