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Why is my 5-year-old dog suddenly aggressive, biting, and attacking?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed | Male | neutered | 5 years and 1 month old | 55 lbs

We have a dog who is 5 years old. In the past few months he's been getting aggressive towards us. Like if we were to scold him or even before we would for something that he knows that he's not allowed to do, he would growl at us and he's now starting to snap or bite us. He has also attacked one of our dogs out of the blue for no reason. He gives no warning when he's going to do it and it's beginning to worry us in the house. Could there be something going on with him that we don't know about?

2 Answers

Most Helpful Answer

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Answered By Rosemary Barber, DVM

Veterinarian

Published on March 20th, 2017

Oh dear! That is a worry for sure! It's really important that you don't get hurt, because dog bites can be pretty serious. I would suggest making an appointment with your vet to talk about possibilities. They might be able to link you up with a behaviorist, or dog trainer that could help a lot. There also could be medications that might help. Or, like you said, there could be a medical problem that is upsetting him.

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    Answered By Jessica Keay, DVM

    Veterinarian

    Published on May 28th, 2017

    Your dog should have an exam by the vet to be sure he isn't suffering from a painful condition that could be causing him to be grumpy and react by biting. If they are unable to find a cause then he should see a veterinary behaviorist for an evaluation to determine if he could benefit form behavior modification. This is especially important if he is snapping at children as this is dangerous and unacceptable. Until the issue is addressed your dog should not be in contact with any other individuals, especially children.

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