Pet Care

How Will Neutering Change My Dog?

A very happy brown Pit Bull smiles outside

You’ll gain medical and behavioral benefits by having your male dog neutered. You’ll also help control the pet overpopulation crisis, which results in millions of healthy dogs and cats being euthanized (humanely put to death) each year in the United States simply because there aren’t enough homes to go around. While the traditional age for neutering is six to nine months, puppies as young as eight weeks old can be neutered as long as they’re healthy. Dogs can be neutered as adults as well, although there’s a slightly higher risk of post-operative complications in older dogs who are overweight.

Medical Benefits

There are significant medical benefits to be gained from neutering your dog. Neutering prevents the following medical conditions:

  • Testicular cancer. Neutering removes the testes and eliminates the risk of your dog developing testicular cancer, a common and life-threatening cancer in older male dogs.
  • Prostate problems. Without neutering, your dog’s prostate will gradually enlarge as he gets older. This can become uncomfortable for him and even make urination difficult. If the prostate becomes infected, it’s difficult to treat without neutering. While neutering doesn’t completely guard against prostate cancer, it does prevent enlargement and possible infection of the prostate.

Behavioral Changes

The only behaviors influenced by neutering are related to male sex hormones. Neutering won’t affect your dog’s working abilities, friendliness, playfulness or personality. However, hormones like testosterone are reduced by neutering, which can reduce behaviors associated with them. You may see a reduction in the following behaviors after neutering your dog:

  • Urine marking. Testosterone makes a dog more interested in advertising his presence by urine marking. Neutering your dog will reduce his desire to excessively mark his surroundings with urine. This includes areas outside and around your yard, as well as inside your home.
  • Roaming. Unaltered dogs often try to leave home in search of females in heat, which puts them at risk of getting lost and being injured or killed on roadways. Neutered dogs tend to live longer than sexually intact dogs, probably because they’re less likely to engage in risky behaviors like roaming. Neutering will lessen or eliminate your dog’s urge to roam.
  • Aggression. Some studies suggest that neutering can decrease aggression toward other male dogs because testosterone might increase the likelihood of aggressive behavior. Other studies have found no significant relationship between aggression and neutering. It’s possible that competition for mates results in aggression between male dogs, so a dog’s urge to fight with other males might go away when his desire for females is eliminated by neutering. However, there are many complex reasons why dogs fight, and you may not see any changes in your dog’s aggressive behavior simply because he’s been neutered.
  • Social problems. Other male dogs can easily detect an unneutered dog’s high testosterone level and become aggressive. This can make your intact dog a target of harassment by other male dogs. Neutering can reduce or eliminate this undesirable attention.
  • Inappropriate mounting. Your dog might be less likely to mount other dogs, people and inanimate objects after he’s neutered. However, mounting is a complex behavior. It can be a sexual behavior, but it can also be a playful behavior or an attempt to assert social control. Only sexually motivated mounting can be reduced by neutering. And although a dog’s interest in females in heat will diminish after neutering, it might not be completely eliminated. He might still become aroused and try to mate if he encounters a receptive female.

To prevent the development of the behaviors listed above, it’s best to neuter your dog before he reaches sexual maturity at six to nine months of age. That way, he’s unlikely to develop unwanted habits. If your dog has practiced these habits for months or years, they might persist even after neutering. However, if you have an older dog, it’s still a good idea to neuter him. Even if you can’t completely get rid of his problematic behaviors, you might see them less often after he’s neutered—and neutering will still be beneficial to his physical health.

If your dog still has habits that you dislike after you neuter him, like excessive urine marking, roaming, aggression or inappropriate mounting, it’s best to seek professional advice. Getting help is particularly important if your dog has an aggression problem. Please see our article, Finding Professional Help, for information about locating a Certified Applied Animal Behaviorist (CAAB), a veterinary behaviorist (Dip ACVB), or a qualified Certified Professional Dog Trainer (CPDT). If you elect to hire a CPDT because you can’t find a behaviorist in your area, be sure to determine whether she or he has professional training and extensive experience in successfully treating aggression, as this training and experience are beyond what CPDT certification requires.

A Common Myth

Neutering as a Quick Fix for All Behavior Problems

Some people think that neutering a dog will immediately get rid of all his behavior problems. Although it often reduces undesirable behaviors caused by a higher level of testosterone, there’s no a guarantee that your dog’s behavior will change after he’s neutered. Although the surgery will reduce the amount of testosterone in your dog’s system, it won’t eliminate the hormone completely. The effects of neutering are largely dependent on your dog’s individual personality, physiology and history.

Neutering is unlikely to change fearful or aggressive behavior toward people or other dogs unless the aggression is specifically related to competition over access to female dogs. If your dog continues to have serious behavior problems after he’s neutered, please see our article, Finding Professional Help, to locate a behavior expert near you.

Potential Detriments of Neutering

Although neutering is beneficial in many ways, there are a few potential effects to be aware of:

  • A small percentage of male dogs become attractive to intact male dogs after being neutered. Other male dogs may become sexually aroused and try to mount your neutered dog.
  • Dogs neutered before they’ve stopped growing may grow slightly taller than they would have had they not been neutered.
  • There is a very slight increased risk for neutered dogs to develop osteosarcoma and hemangiosarcoma (two kinds of cancer), particularly those breeds that are already predisposed to these diseases.
  • Dogs neutered prior to five months of age may be slightly more likely to develop hip dysplasia and cranial cruciate ligament (CCL) rupture, particularly those breeds that are already predisposed to these diseases.
  • Neutered dogs are at increased risk of developing hypothyroidism.
  • Physiological changes after neutering may affect your dog’s metabolism and appetite, making him prone to weight gain. There’s some evidence to suggest that puppies neutered before five months of age are at greater risk of becoming obese than puppies neutered later. This potential drawback is easily controlled with appropriate diet and exercise. If you notice that your dog looks overweight, you can decrease the amount of food you give him and increase his exercise. If you’re not sure if your dog’s weight is appropriate, please consult your veterinarian.

It’s important to realize that the potential drawbacks of neutering are minimal relative to the benefits. However, you should discuss both the pros and cons with your veterinarian to make the best decision for the health and well-being of your individual dog.