Why is my dog suddenly aggressive and grabbing other dogs' necks?

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.

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.

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.

Biting aggressively is a serious concern and a very complicated thing to deal with. Leash aggression can sometimes manifest and be redirected toward the person putting on the leash, however if this suddenly happened out of the blue I'd be concerned. A good first step with any behavioral issues that comes on suddenly is to schedule a vet visit to rule out any issues such as pain or illness. Something wrong such as a slipped disk causing pain in the neck or shoulders may make having Griffy's collar or neck handled painful, causing him to bite. If he checks out healthy, talking with a trainer or behaviorist in person is a good next step. They can work with you on a plan to gradually reintroduce the leash to Griffy through positive experiences (such as giving a treat when you bring out the leash, gradually getting him used to it again, etc) and can observe in person what exactly is going on to better tailor the plan. A veterinary behaviorist can also work on both medical treatment and behavioral treatment at the same time to make things less stressful for both you and Griffy. If he is attempting to break the skin while you put the leash on, refraining from doing so until you've talked to a trainer or behaviorist in person is best. You can find a list of local behaviorists in your area by checking out this link: http://www.dacvb.org/about/member-directory/

Hello. I’m sorry to hear about the trouble you’re having with Little Miss Blue. Is there any chance she could be pregnant? I noticed that you listed her as not spayed. Pregnancy can cause aggression especially if they are close to having puppies. If she is not pregnant sometimes dogs that are painful will start showing aggressive behavior suddenly. I would have your vet examine her and make sure that she is OK and not suffering from any thing painful, also it may be good to have them run for blood work and make sure nothing else is wrong. I would start there and if she’s healthy and not pregnant I would try to find a behaviorist to work with to alter these aggressive tendencies.

Abrupt changes in behavior like this in dogs is very concerning to me. I would be worried about some underlying neurologic disorder that could be going on. If nothing has changed at home, her routine, or the environment in general, then I would suspect an underlying medical issue. I would recommend taking her to be examined by your veterinarian and possibly having some lab work performed so they can try and determine what is going on. Your vet may recommend further work up by veterinary neurologist or may recommend a behavior modification drugs like Xanax or Prozac. I hope this helps. Thanks for using Petco Pet Education Center, formerly Petcoach. Best of luck.

Any continued abnormal symptoms (longer than 24 hours) warrants a vet exam. I cannot tell you what is wrong with him just by your description. I can tell you that you need to be diligent about getting weird behavior changes checked out . Behavior changes could be due to an underlying medical issue (pain somewhere in his body, vision problem, etc) or a behavioral issue. It is always best to rule out an underlying medical issue first before just assuming it is behavioral. I suggest you get him to a vet for an exam.