Why is my 1-year-old dog suddenly aggressive towards other pets?

Unfortunately, it's relatively common for behavior issues like this to develop between 1 and 2 years of age - this is the period when dogs reach social maturity. Often, they may have been fearful or nervous about many things when they were puppies, but don't start to act out aggressively until they are a bit older. Aggressive behavior in a large dog like this can be a serious problem, and is best treated by a professional who can work with you and Molly in person. I would recommend making an appointment with a veterinary behaviorist who can evaluate her and put together a treatment plan to work on the problem. You can search for a board-certified veterinary behaviorist here: www.dacvb.org In the meantime, I would recommend keeping her away from people and dogs as much as possible for safety reasons, and to avoid making the problem worse. Treatment for this problem is generally based on teaching the dog to associate good things (such as treats) with seeing people or other dogs, starting at a distance where they are comfortable and gradually working close from there. The behaviorist can help you with this, since it can be hard to do on your own! Punishment of any kind for this behavior (including verbal scolding, leash corrections, shock collar corrections, etc.) is not recommended, as it tends to make the dog more fearful and has a high risk of worsening the aggression over time.

Bella is adorable. I would recommend taking Bella to the veterinarian to make sure there is nothing medical going on with her. If that comes back as just behavioral I would recommend getting a trainer to work with you and her. They will be able to see what is the trigger and work with her and you to stop the behavior. If the trainer evaluates her and determines medication is needed then your veterinarian can provide medication to help. Thank you for using Petco Pet Education Center, formerly Petcoach.

I'm sorry to hear that you're having this problem! If this has been a fairly sudden behavior change for Elsa, the first thing I would suggest would be to have her examined by a vet to see if there may be a medial reason for the aggression - many illnesses including thyroid problems and neurologic issues can cause sudden mood swings and behavior changes like this, as well as anything that may be painful such as an injury of some kind, arthritis, etc. If your vet determines that Elsa is healthy, then I would strongly recommend making an appointment with a veterinary behaviorist as the next step. Aggression towards humans is a serious and complex behavior issue that needs to be handled by a professional who can work with your dog in person. The behaviorist will evaluate your dog and help you determine what is triggering the aggression, then put together a detailed training plan to work on the problem. You can search for a board-certified veterinary behaviorist in your area here: www.dacvb.org

Thank you for submitting your question regarding Lily. I would start by having her see her veterinarian. She will need a thorough examination and laboratory work. Most cases of behavior changes are due to an underlying medical condition. Pain somewhere in her body could be causing her to act out aggressively. A neurological condition is less likely. If a medical problem is not identified, then anxiety should be considered. Medication options can be discussed if this is thought to be the case. I hope this information helps!

Hi and thanks for using Petco Pet Education Center, formerly Petcoach! Sorry to hear about Bruno. When a puppy shows aggression, I immediately advise neutering him to remove the male hormone-driven behaviors. I would advise taking him to your veterinarian for their opinion also. He may have some medical reason for his sudden onset of aggression. Your vet can gather a history, perform an exam and then offer a diagnostic/treatment plan based on their findings. Possible tests include fecal/blood/urine tests and x-rays to look for underlying medical problems that could cause aggression. If a behavioral problem is suspected, then neutering, behavior modification, and drug therapy can be tried. I wish you good luck with Bruno

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.

How long ago was it when she was spayed? If it was very recent, is she on pain meds? If not then I would recommend discussing this with your veterinarian and see if they can put her on some type of pain medication. If it wasn't within the last week then it most likely has nothing to do with pain related to the spay and there may be something more going on which would require a vet visit and potentially a trainer. Thank you for using Petco Pet Education Center, formerly Petcoach.