Do neutered dogs get along with unneutered dogs?

Many pet owners get their dog neutered in an effort to reduce aggression. However, this doesn’t always work out the way they planned. It can be particularly problematic when a neutered dog is around an intact male. 

Do neutered dogs get along with unneutered dogs?

Some neutered dogs get along well with unneutered dogs. However, aggression from the neutered dog towards the intact dog is common. Neutered dogs are expected to be less aggressive and territorial, so pet owners wonder what the problem is. It turns out that there are several reasons your neutered dog may be aggressive towards an unneutered counterpart.

Neutering and Testosterone

A neutered dog has their testicles removed. Testicles produce the majority of their testosterone. Essentially, testosterone is responsible for male behavior in dogs and other mammals. Neutering your dog can reduce some behaviors, including unwanted aggression.

However, it is limited to aggression that is the result of testosterone, usually dominance related aggression. Recent research has shown that contrary to popular belief, neutering can cause an increase in aggression.

Testosterone is responsible for many dog behaviors. It certainly causes dominance behaviors and sexual desire. However, it also makes the dog feel confident and secure. 

When testosterone is drastically lowered due to neutering, the male is less likely to urine mark and roam away from home. However, aggression, particularly fear based aggression, is increased. 

Neutering and Increased Aggression

There are two basic reasons why a dog exhibits aggressive behavior. It’s essentially the same as it is for humans.

The first reason is dominance. The dog wants to be dominant over another dog, protect their territory, or they want a resource the other dog has. In human terms, this includes a bully who beats someone up for their shoes, as well as someone who protects their property from intruders. 

The second reason is fear. Humans and dogs often become aggressive when they are scared. Both humans and our canine counterparts have a fight or flight system that activates when scared. Neutered dogs are more likely to be afraid, and to act aggressively out of fear. 

Do neutered dogs attack unneutered dogs?

Neutered dogs can attack unneutered dogs. However, it’s not as common as you might think. When it comes to a neutered male and an intact male, the bark is typically worse than the bite. 

Male vs. Female Aggression

Males are more likely to act aggressively, but are less likely to fight than females. When two female dogs fight, they often injure each other. In fact, a fight between two females can even result in death. This is particularly common if the two have a history of fighting with each other. 

Males, on the other hand, tend to act aggressively. They will exhibit aggressive  behavior, but it’s rare that it progresses beyond that. It is possible for a neutered male to attack an unneutered male, so it’s wise to monitor them when introducing a new dog. 

Alpha Behavior

Dogs who live in packs have a hierarchy. Within a pack, there is typically an alpha male and female. These two are the leaders of the pack,and other dogs submit to them. The next rank is beta. These dogs are submissive to the alphas, but dominant to other dogs. The last position is omega. Omega dogs are subservient to the betas and alphas of the pack. 

It was once thought that most dog aggression resulted due to a fight for dominance. However, this isn’t always the case. Once the roles are established, aggression typically decreases. 

Neutered dogs are usually more submissive, putting them in a beta or omega role within the pack. You may not think of your household as a pack, but your dog does. 

You are, or should be the alpha of the house. The dominant dog in the house will take on the beta role, and subservient dogs will take on the omega role. 

Many owners make the mistake of trying to be fair, and actually disrupt the natural order of the pack. If you have multiple dogs, one dog will naturally eat before the others. They will also get the first choice of treats and toys. While this may seem unfair from our perspective, all dogs are calmer and more secure when they have a well defined role within the pack. 

Male Scent

Dogs use scent as their primary scent. They can identify individuals solely through scent. They can also detect sickness, health status, and sexual maturity.

Intact males have the scent of a male dog. Neutered males have a scent similar to a female dog, because they have a low level of testosterone. The scent of a male can make the neutered male feel threatened. He may act aggressively out of fear. 

Do neutered dogs react to unneutered dogs?

Neutered dogs can react to unneutered dogs. How they react will depend on a number of factors, including socialization, previous experience with unneutered dogs, and the age when they were neutered. 


Socialization is a process of allowing your dog to meet other dogs. Dogs’ first social experiences begin with their mother and littermates. They learn valuable skills and rules of behavior during this time. 

At 8 weeks old, or around the time they are weaned, it is important to introduce them to other dogs. The period between 8-16 weeks is critical for proper socialization. 

The puppy is still in the learning stage at this time. When they are socialized properly, they will be accustomed to interacting with different types of dogs, including neutered and intact males. 

In addition to socializing them with other dogs, you should expose them to new people and experiences. Dogs who are socialized well as a puppy are less likely to be fearful or aggressive as they age. 


Ideally, socialization is always a positive experience. However, it doesn’t always work out this way. Dogs have a strong associative memory. This means they will remember that something good or bad happened, even if they don’t remember the specifics. 

Training works based on associative memory. When your dog follows a command, they get a treat. They quickly learn that when they perform the desired behavior, a positive experience follows. This makes them want to repeat the behavior. 

This also holds true for negative experiences. Punishments are no longer a recommended part of dog training, because they can be ineffective. However, they work on the principle of association. 

An experience doesn’t have to appear traumatic to affect your dog. You may expect your dog to react negatively to intact males if they were injured by one in the past. However, it may be the other dog’s loud bark startled them. It could even be a vehicle driving by that scared them, and not the other dog. These situations may seem insignificant, but if it had an affect on your dog at the time, it can cause negative association.

Your dog may fear or act aggressively towards intact males, because they associate the negative experience with them. 


Age plays a critical role in dogs developing aggressiveness after neutering. Dogs neutered before puberty are much more likely to be overly excitable, nervous, and aggressive than those who are neutered later. 

It’s thought this is because the testerone plays a role in brain development. It essentially wires the dog’s brain to be a male. This means a dog neutered later may still display some male behaviors like marking, but to a lesser extent than intact males. It also allows them to develop confidence and learn how to interact with the world. 

Recent recommendations suggest waiting until a male is at least 1, and ideally 18 months to 2 years before neutering to prevent unwanted behaviors due to neutering. 

Can a neutered female and unneutered male dog be together?

Yes. There’s usually no issue with a spayed female and an unneutered male dog being around each other. Many pet owners have had this combination and report no issues. 

Males usually only go crazy over a female dog when they are in heat. Because a spayed dog doesn’t have heat cycles, this shouldn’t be an issue. 

You may notice some typical dog behaviors, like attempting to assert dominance. As long as they aren’t violent or aggressive, it’s best to let them sort out dominance on their own. 

Will the Male Hump the Female?

Dogs of both genders hump for a wide variety of reasons. Some owners see this as a natural part of dog behavior, while others find it undesirable. If it’s a problem, your dog can be trained not to hump. 

Humping is often an invitation to play or an attempt to assert dominance. If the female is not in season, it’s usually not sexual. However, excitement and sexual arousal are very closely linked in the brains of dogs, and humans, for that matter. So a dog that gets excited while playing may start humping, transferring one type of excitement to another. 

How to get my neutered and unneutered dogs to get along?

If your neutered and unneutered dogs aren’t getting along, there are some things you can do to remedy the problem. 

Neutering an Intact Dog

Neutering your intact dog may be the solution. Keep in mind that neutering later rather than sooner often gives a better outcome. It’s also important to note that neutering will only eliminate dominance-based aggression. If the aggression is fear based, neutering will have no impact, and may increase aggression. 

However, if your neutered male has an issue with the intact male, neutering the intact male could solve the problem. It will take time after neutering for testosterone levels to lower. This usually takes 4-8 weeks. Once their testosterone levels have lowered, your neutered dog may no longer be triggered, because the recently neutered dog no longer smells like a male. There is no guarantee, however. 


Prevention is best for this issue, but it’s never too late to work on socializing with your dog. Experts recommend starting with walks. This can allow your dog to encounter other dogs and people along the way. 

If you have a friend with dogs, invite them over for play sessions. If possible, expose your dog to both intact and neutered males during these sessions. 

Once they’ve gained some social skills, bring them to a dog park. 

Throughout this process, you’ll need to watch your dog’s cues. End the sessions when they begin to appear anxious or show the first signs of aggression. 

Professional Help

Your vet can be a trusted starting point for seeking professional help for behavioral problems. Many owners find that a dog behavioral specialist can provide solutions to many behavioral issues, including aggression. 

They will work with you and your dog to eliminate unwanted behavior. Even if you choose to have the intact dog neutered, a behavioral therapist can still provide helpful advice. 




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