What is wrong with my boyfriends dog?

Definitely what Lenka (Lenna) said about weight and the need to go to a vet for a health check up. It could be, if his health is suffering, that is causing his behavior. He could also have a brain issue that causes his behavior problems (it's not totally common but the vet should be able to indicate if he has some neurons misfiring in his brain). But it could be the dog has behavior issues separate from any health issues. In this case, and possibly even if it's due to health issues, he likely needs behavioral training. There are many great behaviorists that can work with the dog and the household members. It's going to take time, patience, and, yes, money, to go through the training to help the dog overcome his anxiety and anger. Good luck!

A miniature bulldog weights less than 45 lbs. If the dog weighs more than you (and I assume you're an adult), then the dog is extremely overweight and unhappy, most likely suffering from some kind of an illness and definitely should be checked out by the vet to see what causes him pain/anger. Good luck.

Hi, Alyssa! As a bulldog mom, my hunch is that your boyfriend's dog has some unresolved separation anxiety issues from your boyfriend leaving for a year and then coming back with a new, unfamiliar human. In my experience, bulldogs can be particularly possessive of their people and definitely know how to hold on to a grudge; when my little guy is feeling jealous or angry, he tends to make VERY intentional eye contact with us and then engage in a behavior he KNOWS is bad to communicate his dissatisfaction.

To second what Lisa said, it will likely take a lot of time, effort, and consistent training to try to resolve these behaviors. I would absolutely recommend consulting with a trainer in your area to discuss the dog's behavioral needs before you or someone else in the home is seriously injured. It's a sad reality that dogs cannot communicate their frustrations with us, and we're often left scratching our heads trying to understand why they are so upset! A great trainer will be able to provide insight and assistance with slowly building the dog's confidence and eliminating aggressive behaviors. Good luck!