Why is my 11-year-old unspayed Pit Bull aggressive to other animals?

I'm sorry that you're having this problem with Cssh! Aggression issues between dogs can be very complex, so without being able to actually meet him in person and observe his interactions with the other dogs, it's very difficult to say what might be causing this. Some dogs simply don't get along well with "new" dogs once they have grown out of their puppy stage - this could well be the case with your dog, since he's about 6-7 months old now. This isn't necessarily abnormal, but it may mean that your dog is not a good candidate for casual socializing with strange dogs. If you want to try and get a better idea of what may be causing Cssh's aggressive behavior and see if anything can be done to improve it, I would recommend making an appointment with a veterinary behaviorist - he/she can evaluate your dog in person and help you understand exactly what is happening. If needed, they can also help you put together a detailed plan to work on the problem. Your veterinarian should be able to find out where your nearest veterinary behaviorist is located, and set up a referral for you if you wish. In the meantime, I would recommend not allowing Cssh to interact with any dogs that he doesn't already know and like since there is a significant risk that he will continue to behave aggressively, which could cause injury to him or other dog.

Some of this may be curiosity and not knowing manners on how to act around new dogs. Some dogs have a different personality and manners on a leash vs. off a leash. She is young enough that seeking a trainer to help socialize her both on and off leash, in new settings, and around new and familiar animals will help her behavior. The more interactions at a young age, the better as long as they are controlled and the proper behavior rewarded

Many times when dogs get older they get arthritis and they hurt so that is why they get grumpy. I suggest you have her to your vet for an exam. If she has pain somewhere the vet can prescribe medications to make her feel better.

Thanks for using Petco Pet Education Center, formerly Petcoach! Spaying can certainly correct aggressive behaviors or tendencies so that is something that can certainly help in Luna's case. If that is not corrected after surgery or you prefer not to spay her, I would highly suggest a qualified dog trainer or behaviorist that can help you with this in person. While correcting these types of behaviors is possible, it usually requires in person training. Good luck and have a great day!

This may require professional assistance. Have her examined by your veterinarian to rule out medical causes for her behavior. Your veterinarian may dispense medication to help. A certified trainer or veterinary behaviorist should be consulted afterwards to help desensitize or acclimate Misty to other dogs. In severe cases, a combination of medication and behavioral modification is needed to overcome problems.

The answer very much depends on why he's aggressive (fear-based, territorial, play-based, etc) but my general recommendations are to stop ALL punishments, avoid anything that is causing aggression, and never allow him around children. Then you need to find a veterinary behaviorist to work with who can go over a detailed history and diagnosis and treat his issues. If you are unable to find a veterinary behaviorist, your vet may be able to start him on medications and talk about some behavior modification.

Yes, she might be more protecive since her puppy is around. You can try an Adaptil collar and Solliquin chews and see if that helps with any stress/anxiety. You could also take her to a trainer or behaviorist but if she is biting your friends then you may need to confine her when friends come over.