Dog suddenly attacking his longtime companion

Dear Cathy: My daughter and I both have rescue shih tzu mixed breeds who have played together for the past four years.

Recently, my dog, who is three years younger than my daughter’s dog, has started attacking him. There is no provocation at all. Her dog will be just lying on the floor and my dog will start attacking him. I had a trainer here and she thought it was territorial issues, but I am sure that is not the case.

We are beside ourselves and do not know what to do or why this is happening. I cannot keep spending money on trainers, so I thought you might have some insight to our problem.

Both these dogs are calm and loving in their own environment. When you walk them outside, they are fine. They love people and dogs alike. I hope you can help me. — Gloria, Coconut Creek, Florida

Dear Gloria: Because this is a new behavior, take your dog to the vet to rule out any medical problems that might impact how a dog behaves. Next, introduce some plugin canine pheromones around the house and get pheromone collars for both dogs to ease tensions.

If your dog is healthy and pheromones are in place, then it’s time to teach both dogs to “leave it” and “come” on command, so they learn to disengage and listen. Begin by putting a treat on the floor. (Always separate dogs during training.) Put your dog on a leash and walk him by the treat. When he looks at it, say “leave it.” When he looks at you, use a reward word, such as “bingo,” and give him some treats.

Over time, you can increase the value of what he needs to ignore, including walking him on a leash by your daughter’s dog. Always reward him for doing as you asked.

I also recommend you and your daughter both walk these dogs at the same time, several times a week. The walks provide the dogs positive time together, and exercise, which can reduce negative behaviors overall. A tired dog is generally a better-behaved dog. Let me know how it works.