My dog suddenly snaps at other dogs. Is it anxiety or aggression?

I would make sure the dog that has become aggressive isn't having any other issues like pain or discomfort. Also, has anything change in your schedule or house that could have made her feel more insecure or anxious? You could talk to your vet about starting her on an anti-anxiety medicine like fluoxetine as this may help. I would also make sure they aren't becoming aggressive over any treats, bones, toys, etc. I hope this helps and she starts to act like herself soon.

Hi there and thank you for using Petco Pet Education Center, formerly Petcoach to address your concern. A sudden change in behavior could be due to a systemic infection / disease, neurological condition or anxiety that has worsened from a stressful experience. I would recommend having a veterinarian examine Marshall so that the most appropriate diagnostic and treatment recommendations can be made. I would have his blood tested including his thyroid level to see if there is an explanation for this behavior. If everything comes back normal, then I would recommend having Marshall go through a behavioral class and consider anti-anxiety medications if no improvement. I hope this helps guide you in the right direction. Please let me know if you have any other questions or concerns and I would be more than happy to help you further.

There are many possible reasons for this, I'm afraid - aggression is a complex behavior issue, so it can be hard to provide a succinct answer in this format. Many dogs develop aggression issues related to fear or anxiety around the age of 2-3 when they reach social maturity, so it's possible that this may be the issue. Or, since I see that Chucky is a bit older than that, he may have a medical problem causing him to be painful or uncomfortable - this is a common reason for "new" aggression in a previously friendly dog. I would recommend having Chucky examined by a vet as a good first step - he/she can check for anything that may be causing him pain or making him not feel well, and get him started on treatment if needed. If everything is normal medically, then it would be best to make an appointment with a veterinary behaviorist to help you determine what is causing the aggression - he/she can observe your dogs in person and also give you a step-by-step treatment plan to work on the issue.

It certainly sounds like anxiety to me - it sounds like your dog is fearful around new people and dogs. I'd recommend talking to a behaviorist or trusted trainer about working on some behavior modification that could help your dog feel more confident in new situations. Ask your vet who they would recommend in your area.

Before assuming this is a behavior issue, I would want to rule out a possible medical issue first. When I hear about sudden changes resulting in aggressiveness, the possibility of pain or discomfort in one of the dogs could be the root of the problem. When a dog is not feeling well, it is only natural for it to react in a negative way if one of its buddies is trying to get it to act normally. A thorough physical exam should be performed by a veterinarian in order to rule out any sort of orthopedic or neurologic pain. Thyroid conditions can also be responsible for behavior changes as well. If it turns out that no medical issue can be be identified, you will have to start considering what may have started this sudden change of heart by Mill. You will have to think back to when it started, when the problem occurs most, where it occurs most, who is around when it is occurring, who ISN'T around when it is occurring, so on and so forth. These types of issues can be long and complicated to resolve, but usually as soon as the issue is identified the road forward becomes much easier.

Anxiety can lead to aggression, and it may be Skye's anxiety has gotten so great that she is now acting aggressive. I'd have her seen by a vet for this to discuss putting her on anti-anxiety medication.

You should definitely have him neutered and getting professional help is a great idea. In the meantime, you could start teaching him the "look" command so you can use this command when you want him to focus on you instead of another dog.