Why Does My Neutered Pup Hate Unaltered Dogs?

At first, it seemed like a funny fluke. When a new neighbor moved in with his Goldendoodle, I noticed that my little pup Frasier could not stop barking at him. No matter where we were, and no matter what we were doing, if Frasier spotted his nemesis anywhere — in the hallway, across the street, or even yards down the block — his back would stiffen. He’d dig his feet into the ground. He’d yap and snarl and growl, and even after the poor ’doodle was out of his sight, he’d stomp around, ranting with his whole body as if to say, “He just makes me so mad!”

Eventually, I noticed something about our household’s Public Enemy No. 1: he was a male dog who had not been neutered. Frasier hadn’t met many unaltered dogs, and suddenly, I began to wonder if that could be the reason for his unseemly outbursts. A couple years later, when another neighbor moved in with an intact Border Collie, I got my answer. Just like with the Doodle, Frasier unleashed a kind of fury I’ve never seen in any other scenario. Naturally, that sent me down a Google rabbit hole.

It turns out, my little Fras isn’t the only neutered pup who cannot abide the company of those with balls. From Reddit to Quora and other forums, some dog parents have noticed that same brand of Freudian animosity. For a while, I figured this was just a dog thing. But then I began to wonder why other neutered dogs in our building did not seem to mind the presence of those our household had labeled “the fecund ones.” At long last, I decided the internet alone could not unravel this for me. It was time to ask the experts. Here, for our collective edification, is what they had to say.

Can dogs tell when another dog is neutered or spayed?

Chances are they can. In addition to their primary olfactory system, which they use to smell all the things we can smell, dogs also have the vomeronasal organ, which allows them to communicate chemically in ways humans can’t even perceive. 

“That goes to more directly, the emotional system of the brain,” says Dr. Julia Albright, a veterinary behaviorist at the University of Tennessee. “There's a whole ’nother world out there, [and] we just don't even know what they're able to detect.”

Think, for example, about when a female dog is in heat. These dogs will release powerful pheromones that male dogs can detect through their vomeronasal organ. From there, both animals’ bodies will begin preparing for courtship. 

Board-certified veterinary behaviorist Lisa Radosta (DVM, DACVB) agrees. “Presumably,” she says, “intact dogs, both male and female, will have different compounds that are released that any dog should be able to smell at least as different or new.”

Do all neutered dogs respond aggressively to intact males?

Not always. Albright says this is not a common behavior, and while Radosta has heard of this behavior from daycare supervisors and pet parents, she has not personally seen it as a persistent pattern.

“I have an intact female and a neutered male,” Albright says, and she also knows a lot of people who have one neutered dog living peacefully alongside an unaltered male. 

Well, there goes my half-baked theory that my dog feels instinctually jealous. So, what gives?

Why does my neutered dog hate unaltered dogs?

If your neutered dog is responding negatively to an unaltered male, there are a few possibilities. Chances are, the behavior comes down to how the other dog is acting or past experiences your dog has shared with intact males.

Bad posture

If your dog is freaking out at a long distance or in a busy environment, there’s a chance it has more to do with the other dog’s behavior than whether or not they’ve been neutered.

“It's usually something about that other dog,” Albright says. “That dog is stiff, that dog barked at him first. Maybe it’s the size of the dog.” As a certain sea witch once said, don't underestimate the importance of body language.

Bad memories

Just like our bad memories can predispose us against certain people and situations, our dogs sometimes react the same way. “Every dog has a temperament, lived a life, and they've had experiences,” Albright says. 

If your dog can’t pass by a neutered dog without throwing a fit, she says, you might begin looking back at their past. Maybe your dog got attacked by a neutered dog, or maybe something scary happened around a neutered dog. That could be enough to make your pup wary.

Novelty

Our pups don’t always know what to do in the presence of something (or, in this case, someone) they’ve never seen before. Statistically in the United States, our dogs are less likely to encounter unaltered males, so they’re likely not as familiar with how they act and smell. 

“Things that are unfamiliar often lead to uncertainty,” Radosta says, “and when animals are uncertain, their behavior changes very often in a defensive way.”

Should I be concerned about this behavior?

It’s never good when your dog gets aggressive with another dog. As Albright puts it, “We should avoid and/or try to modify that.” At the same time, she adds, “One of the most difficult things to do in my position and as a pet parent is getting involved in inner dog issues. We're not dogs; it's difficult to know what they're picking up on.”

Radosta agrees that pet parents should always pay attention to our best buds’ interactions with other people and animals. But she, too, stops short of saying we should always intervene. “Our pets can't talk to us,” she says, “and it's our job to be looking at situations and seeing whether our pet is handling that specific situation, instead of labeling [it] as always safe or always dangerous.”

At this point, I’ve accepted that we’ll probably never know why my sweet baby Frasier becomes so sour in the presence of a peer who’s never gone under the knife. But you know what? I’m sure he has his reasons. Whatever they are, we support his journey.