Castration, or neutering, is a surgical procedure in which both testicles are removed. It leaves the castrated dog infertile (unable to produce offspring). Because testicles are one of the endocrine glands that produce the hormone called testosterone, the production of this hormone is stopped. After the production of testosterone has stopped, there are some behavioral changes to be expected in male dogs. However, not every aggressive behavior is related to testosterone levels. This leads us to conclude that castration helps in some and doesn’t help in some other cases.

When Does Castration Help?

First of all, it takes around 4 to 6 weeks after the surgery for testosterone levels in the blood to drop to negligible levels. This means that even after castration, a dog might behave as if intact for some time. But, eventually, the levels will drop and we can expect these behavioral changes:

• Roaming can be reduced (by 90%)
• Male-on-male aggression can be reduced (by 60%)
• Urine marking can be reduced (by 50%)

Even though male-on-male or same-sex aggression can be reduced by 60%, it doesn’t always solve the aggression problem. Why? Because aggression is not always induced by the increase of testosterone. In other words, aggression in intact male dogs is not always connected with dominance-based aggressive behavior. Sometimes, it is the case of fear aggression. But, let’s stick to when castration helps and that is the case of offensive aggression.

What is Offensive Aggression?

Offensive aggression is in the majority of cases pointed toward other dogs, especially of the same sex. If this is the case, if a dog acts aggressively towards other male dogs with an offensive stance, we can start talking about castration. However, even then, a veterinary checkup is the first thing to do before deciding to castrate a dog. Maybe there are some hormonal problems of other nature that cause high testosterone.

When a vet gives the green light and concludes there are no other health issues, castration can be a solution.

 If the aggression is always aimed towards other dogs, another solution can be avoiding triggering situations or places. If you don’t have any other dogs but take your dog to the dog park or the aggression happens during the walk when your dog sees another dog, then a solution can be avoiding such places. But, in the end, a permanent solution is castration.

Avoiding other dogs or triggering situations is a preventive measure if you don’t want to neuter your dog and there are no other health issues

When Castration Doesn’t Help

If your dog shows signs of aggression towards other dogs, people, objects, cars, or anything else there is a high probability you will not solve this problem through castration. In this case, a dog will not calm down after castration because fear is not elevated by testosterone. 

On the contrary, testosterone gives confidence. Without testes to produce testosterone, a dog is left with even less confidence than before, leading the dog to act even more aggressively towards perceived threats out of fear. So, the solution in this case is to find what causes fear. What is the dog afraid of?

 If it’s other dogs, avoid contact with those dogs. If it’s a person, such as a vet, make the trip comfortable for the dog. If it is a vet, you can try to connect the trip to the vet with a positive aftermath. For example, treats after the vet or a walk to a dog’s favorite place after the vet. And once again, I’d always recommend a veterinary checkup first to make sure a dog is healthy.

Pain and discomfort can cause aggression in some dogs. Dogs can’t tell us what hurts and how much, but they show us through behavioral changes. Depending on the part of the body that hurts, dogs behave differently. It also depends on the pain level and the dog’s personality. Some dogs will turn depressed, avoiding any activities, or will do it with a whimper or whine. Other dogs will act aggressively. That’s not unnatural, it’s preservation. They are in pain and they don’t want to be touched or they make a connection between a certain place, object, or sound and pain, which consequently makes them aggressive. 

Fear aggression cannot be solved by neutering your dog

Pavlov’s reflex is an example of involuntary behavior after a sound stimulus. Just like Pavlov’s dogs, a neighbor’s dog still barks and acts aggressively towards any car that is not their own after it has been hit by one. He survived, but he never forgot. This is just one example of when a situation that caused pain led to aggressive behavior that cannot be solved by castration.

Pain and discomfort can also cause aggression, so first, take your dog to a vet to rule out any health issues because castration won’t help if it’s pain that is causing the aggression

Final Thoughts

If you are having problems with your dog because it acts aggressively towards other animals or people, the first thing to do is to take your dog to a vet. If the vet says there is nothing wrong with the dog (no pain or discomfort anywhere), then we have to look at the behavior. When does your dog act aggressively and how? If it is only toward other male dogs (or other dogs in general) with a dominant stance, chances are testosterone levels are high and castration can help. If, on the other hand, your dog shows signs of fear aggression then castration won’t help. This is because testosterone makes a dog more confident NOT more fearful. You will only do worse if you castrate a fearful dog. What you need to do is address the behavior with a professional dog behaviorist.

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Cover Photo by Gilberto Reyes