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Sudden Changes in Behavior

Updated: Jan 22, 2021

a dog snarling and threatening another dog

I recently received an email asking for a training referral. The sender had two senior dogs, and the younger of the two was suddenly attacking the older one. There had been problems between the two when they were young, but they’d been getting along for many years. While I did find a trainer for the woman in her city, I also advised her to take both of the dogs in for a complete veterinary exam.


You might be thinking Hmm, a sudden behavior change could be linked to aggressive behavior, but why would she need to take both dogs in? Surely, it’s only the younger one who needs to be seen. While it’s true that the dog who is displaying the aberrant behavior should be thoroughly checked, sometimes the reason the dog has suddenly become aggressive is because the other dog, unbeknownst to the owner, is ill. Think about how in a group of dogs or wolves when the one in charge becomes sick or weak, another member might take advantage of the situation and challenge for rank, especially if his own standing has been suppressed for a while. Dogs often know when another dog is in decline before we do.


Both dogs should have a thorough blood panel done. Vets who are knowledgeable about the effects of physiology on behavior should know what to look for, but it doesn’t hurt to do a bit of research on your own and to share that knowledge with your vet. Check out the link between thyroid levels and aggression, including the work of Jean Dodds, DVM. Look into how issues with the liver can affect canine behavior. Beyond that—and this is something I don’t hear discussed often—I recommend having the dog checked out structurally beyond what normally happens in a cursory veterinary exam. Canine chiropractors are specialists who are much more likely to be able to discern whether a bone is out of place, a nerve is pinched, or something else is happening that’s causing pain or discomfort.


Maybe it’s because I’ve had so many issues with my own back that I understand all too well how, when something is out of place structurally and pain and inflammation strike, anyone can become cranky. Dogs are easily irritated when they’re in pain, and it’s unfortunate that a chiropractic approach is so seldom considered. When my mother was in a nursing home in her late 80s, she kept complaining that her neck hurt. She was clearly in a lot of pain and distress, and though she was normally pleasant and friendly, it made her grouchy and irritable. Who could blame her? The staff kept insisting it was part of what happened “at her age” and just kept pumping her full of pain pills. I told them she needed to see a chiropractor. They wouldn’t listen, and I finally arranged myself for her to be taken to one. One adjustment later and whaddayaknow! The pain was completely gone and she was back to being her own happy self. Doesn’t it stand to reason that something similar could be going on with a dog who was formerly happy and well behaved and is suddenly cranky and aggressive?


Of course, not all sudden aggression has a physiological cause. Changes in the household or the dog’s routine should be considered as well. For example, did someone the dog was close with move out of the home? Did someone new move in? Did a baby arrive on the scene? A change could also be environmental, like a construction site springing up next door. I’m very noise sensitive and can easily understand how a dog who was the same would becoming anxious and might take it out on a canine companion. And what about other senses? Even something like a new cleanser being used in the home could affect an odor-sensitive dog. Chemicals give me raging headaches, and although I haven’t seen any research on the subject, I would think it’s possible that it could happen to dogs as well. And, by the way, it’s not only aggression that can manifest suddenly. If a dog who has seemed fine when left alone is suddenly showing signs of separation anxiety, it may be that he’s feeling needier because he’s unwell or anxious.


Again, many times sudden behavior changes do have roots that are solely behavioral. But when the cause isn’t clear, it’s always best to do some sleuthing to rule out possible underlying factors. After all, if there is a non-behavioral cause, applying behavior modification alone isn’t going to solve the problem. When it comes to sudden behavior changes, a holistic view is always best. And if there’s fighting between your dogs that truly is behavioral in nature, check out my latest book Keeping the Peace: A Guide to Dog-Dog Aggression in the Home for more help. ______________________________________________________________________________ Don’t want to miss anything? Subscribe to the blog to be notified of new posts!

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