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Why are my two male dogs suddenly fighting? Could it be a female in heat?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Medium (23 - 60lb) | Male | unneutered | 60 lbs

We have two brother mixed breed dogs, 2 1/2 years old. Been here since puppies without any aggression or troubles. In past week they have begun to have violent fights. There may be a bitch in heat in the neighborhood? Any suggestions as to cause and cure. Thank you.

1 Answer

Most Helpful Answer

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Answered By Jessica Desrosiers

Veterinary Technician

Published on May 22nd, 2018

It's possible, and if there is, having both of your dogs neutered may reduce the fighting. Other possible causes can include pain or illness, as those can both cause sudden behavioral changes in dogs that may cause them to lash out. I would separate both dogs, and have a vet checkup to rule out any health issues. if they check out healthy, having them neutered may help. If you don't wish to neuter them, it may be a good idea to speak with a trainer or behaviorist in person who can observe their behavior and help formulate a more tailored plan. Slow, careful introductions may help, and if the dogs become too nervous or excited, separating them until they are calm again is best before reintroducing.

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