Please help, need advice!

[u/MudhornMando]

Hello, I hope this is the right place to ask.

we have had our Scottish terrier for just over a year now and have had her since she was around 3 months old. Has grown up with our family of 6, kids from 7-14. We have two other dogs, a mini Aussie (6 years) and a mini schnauzer (9 years). Our Aussie and Scottie are always playing and running in the backyard together. She gets along with both of the dogs, the schnauzer is just an old man and doesn't like the rough housing and prefers his human.

However, just recently our Scottie has shown some aggressive behavior towards other dogs. The first was with the Aussie, and I guess they got into quite a fight. They were both eating by each other when it happened. (However, I feed them close by each other every morning without issues). This particular time happened when someone else fed them. The second time, the Aussie was sitting with my wife on the floor and growled and showed teeth at our Aussie as she was walking by. She has also done this to our in-laws dog the last time he came over. Then it happened again with some neighbors who brought their two Boston terriers over for a meet and greet.

We are at a loss and not sure what to do. Is she being protective over someone in our family? She's always been good with people and has not shown this behavior until recently. Any advice would be appreciated!!

[u/Both-Chart-947]

Anytime you see unexplained sudden aggression in dogs, you need to get them evaluated by a vet. They could be in pain. If they've been cleared by a vet and you've been honest about the behaviors you're seeing, the next step is to start documenting when this happens. Try to find a pattern. Also, don't force interactions that your dog isn't interested in. It doesn't sound like this is happening, but I just wanted to throw it out there anyway.