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My senior dog is suddenly aggressive and growling. Is this normal?

Updated on September 23rd, 2025

Pet's info: Dog | Mixed Breed Large (61lb +) | Male | neutered | 10 years and 4 months old

Do dogs get more aggressive as they get older? Earlier my dog dropped his bone under the couch so I tried to help him get it but he growled and barked at me.

3 Answers

Most Helpful Answer

Answered By Daniel Fonza, DVM

Veterinarian

Published on May 14th, 2018

Hi there and thank you for using Petco Pet Education Center, formerly Petcoach to address your concern. The development of aggression as a dog gets older is not something I would consider to be normal. This behavioral change could be due to canine cognitive dysfunction (think of this as doggy dementia) or potentially something more neurological (brain tumor or degenerative change to the brain). I would recommend having Buddy examined by a veterinarian so that the most appropriate diagnostic and treatment recommendations can be made. There may be something systemic going on so having his blood tested would be a good idea. There are drugs that you can use for doggy dementia such as Selegiline. 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.

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Jenny, DVM
Veterinarian
Published on November 7th, 2017
I would take him to a vet for an exam. Often times in older dogs, they can have aggression due to pain. This is often due to arthritis. Dogs can have cognitive dysfunction that can alter their behavior or a brain tumor. Your vet can check for anything signs that can help differentiate to see what your best options are for medicines
1Pet Parents found this answer helpful
Answered By Jennifer Summerfield, DVM CPDT-KA
Veterinarian, Certified Dog Trainer
Published on May 5th, 2017
I'm sorry to hear that you're having this problem! It's unusual for behavior issues like this to develop out of nowhere this late in life, so yes - it's certainly possible that he may have had a stroke, or some other neurologic problem such as a brain tumor. Certain systemic illnesses like hypothryoidism, Cushing's disease, or pain from arthritis or other problems can also cause behavior changes and increased aggression in older dogs.

I would recommend taking Rio to the vet for an exam to discuss this problem when you are able to. Your veterinarian may suggest blood work, x-rays, or other testing to help check for these problems. Many of them are very treatable once a diagnosis is made, so there's a good chance that your vet may be able to help.
1Pet Parents found this answer helpful

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