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Why Don’t My Dogs Get Along Anymore?

Why relationships change in multi-dog households.

by Karen B. London, PhD
August 27, 2021
Two dogs playfully standing next to each other outside.
Photo: Caleb Woods / Unsplash

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I have two dogs who used to get along so well. Lately, instead of being his usual sweet self, the younger one has become pushy with my nine-year-old senior dog, and it seems to be getting worse. After three years of harmony, why is my younger dog so rude to her, and will he grow out of it?


A family is a dynamic social unit, and interactions between members change—a truism that holds for most, if not all, social species, including dogs. While it can be surprising for many pet parents to see such a shift in a relationship that used to be so smooth—it’s actually pretty common. Here are five reasons why your dogs may have stopped getting along.

1. They’re at different ages…

Younger dogs who’ve been respectful to older dogs often start to assert themselves as they mature and become more confident. Your older dog is likely entering her golden years—even if she’s healthy—she’s probably a little slower, a little less active and perhaps a little quicker to tire. On the other hand, your younger dog is entering the prime of his life—maturing into his full adult status.

A dog’s developmental stage matters because age is a fundamentally important part of how dogs treat each other and get along. Young adults through middle-aged dogs are usually on the receiving end of deferential behavior from other dogs. This is a huge generalization, and of course, there are tons of exceptions based on individual personalities but on the face of it, your dogs certainly fit the general pattern. Your younger dog is demanding more respect and offering less, while your older dog is not able to command the respect she once did.

2. They might be resource guarding…

Resource guarding is one of the “usual suspects” when dogs in a household have issues with each other.As dogs grow from adolescence to young adulthood, it’s common for them to have an inclination to hoard things or defend treasures. If resource guarding is the issue, as the younger dog develops possessiveness issues, he may no longer be willing to defer to the older dog — even if he was previously respectful. Challenges over resources are common, and while his behavior is going to appear disrespectful, he’s actually just asserting his own interests.

3. The younger dog may just be over it…

The younger dog may be saying, “Enough already!” Sometimes, what looks like a younger dog being disrespectful is not what it appears. Your younger dog may be acting less respectful because your older dog has been controlling everything, and the younger one isn’t having it anymore. It’s not unusual for a younger dog to decide that enough is enough with an older dog who’s not been sharing. When the younger dog rejects the older dog’s privilege (as it were), it can appear that the younger dog is being disrespectful, but it’s really quite reasonable for him to stop his across-the-board deference.

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4. They have conflicting personalities…

Individual personalities influence how (and if) this age-related dynamic plays out.It’s pretty common to see dogs who are two to three years old behaving less respectfully to dogs in their household as they get older, especially towards dogs age seven or more. However, personality also plays a role. Like humans, dogs’ personalities likely change over time. Maybe one dog likes to wrestle, and the other doesn’t. Some dogs may be more interested in toys, food, space, attention, or any number of things, while others are wholly unconcerned. If your dog has a strong interest in something, he is likely to assert himself — it’s part of the natural canine social order.

5. There could be a health problem…

Then there are all the age-related physical problems that can impact an older dog’s relationships. Whether the pain and discomfort comes from conditions like arthritis, hip dysplasia, or joint stiffness, dogs with physical issues may be irritable or short-tempered. Compounding the problem, those physical issues can result in a lack of sleep for the older dog, which will add to their irritability. An irritable older dog may not be as sweet and kind as usual, making them seem unpredictable or even scary to a younger dog. It’s only natural that the younger dog acts differently in response, and that can mean behaving less deferentially and more assertively.

Age-related mobility, vision, and hearing problems can also contribute to the deterioration of a previously harmonious relationship. A dog with such issues may not be able to communicate clearly with body language or may not respond appropriately to the younger dog because of an inability to see or hear that dog’s signals. Miscommunication can lead to both confusion and anxiety for the younger dog and they might respond with behavior that seems downright rude.

They won’t grow out of it.

So now that you know why your dogs aren’t getting along anymore, what’s next? Well, their relationship is going to keep changing. Don’t hitch your wagon to the idea that your dog will grow out of it. Your younger dog will continue to mature, and your older dog will continue to age, so this change in the dynamic between the two of them is unlikely to be temporary. Seek out the advice of a qualified animal behaviorist for tips and tricks on finding the right balance.

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karen london

Karen B. London, PhD

Karen B. London, Ph.D., is a Certified Applied Animal Behaviorist and Certified Professional Dog Trainer who specializes in working with dogs with serious behavioral issues, including aggression, and has also trained other animals including cats, birds, snakes, and insects. She writes the animal column for the Arizona Daily Sun and is an Adjunct Professor in the Department of Biological Sciences at Northern Arizona University. She is the author of six books about training and behavior, including her most recent, Treat Everyone Like a Dog: How a Dog Trainer’s World View Can Improve Your Life.