Castration & The Behavioural Effects

Many dog owners inadvertently conclude that canine castration is the magic solution to all their dog-behaviour problems. The decision to castrate is often taken as a desperate measure, rather than a well-thought-out and considered judgement based on the likely benefits.

The main reasons castrations are carried out are usually to either:

Prevent accidental mating and, consequently, unwanted puppies.

Address certain medical conditions including testicular cancer and diseases of the prostate gland. Or/and to address behavioural problems. This article looks specifically at the behavioural implications of castration and avoids both the medical and moral arguments surrounding this subject.

What exactly is castration?

Also known as neutering, castration is the surgical procedure which removes an animal's testicles (or testes). It is a routine minor operation carried out under general anaesthetic and does not normally require an overnight stay at the vet. Some stitching is required which is then usually removed after 7-10 days. Un-castrated dogs are often referred to as 'entire' males.

So what is the connection between castration and behaviour ?

The testes are responsible for the production of testosterone. As dogs grow, during their adolescence (6-18 months) the levels of this hormone increase such that secondary sex-related characteristics become more evident. These include mounting, leg lifting and higher levels of aggression. The hypothesis is that removal of the testes reduces the production of testosterone and hence sex related behaviour.

Does castration reduce dog aggression towards humans?

Of all dog behaviours, aggressiveness is the one that gives us the greatest concern. The reasons for aggression within dogs can be varied. Understanding these reasons, their causes and symptoms requires the experience of a trained behaviourist. The causes for aggression towards family members is usually the most difficult to determine. Often it is as a result of the dog attempting to gain a higher rank within its pack (which includes your family). This is known as dominance aggression and surveys have shown that this form of aggression is more common in entire males than castrated males. In such cases, your vet or behaviourist may recommend castration as part of a behaviour programme to tackle this form of aggression. They would also look at ways to help stabilise the ranking hierarchy within the home. See our article How to become the pack leader.

Territorial aggression is often the main cause of aggression towards visitors to your home. In the wild, territorial aggression by dogs stems from the need to protect mating and food resources. Hence, like dominance aggression, castration may also be part of a behaviour modification programme.

On the other hand, your dog's discomfort with a particular situation or circumstance may result in fear or nervous aggression. There can be a number of reasons for this, but lack of socialisation during ‘puppyhood’ is usually the main cause. In such cases, a behaviour modification programme is unlikely to include castration.

Does castration reduce dog aggression towards other dogs?

Aggression between dogs is most often either fear aggression or dominance aggression. Fear aggression may be the result of a previous experience of being attacked, or because they feel they are unable to escape a particular situation. In the latter case, dogs are more likely to display fear aggression whilst on lead as opposed to being off lead. As mentioned earlier, canine castration would not be a part of resolving aggression caused through fear.

Castration may be recommended where aggression between dogs is orientated towards other males and where fear aggression has been ruled out. Castration may reduce the desire to dominate and reduce overall aggression thresholds. Additionally, castrated dogs smell less masculine and are less likely to be the focus of aggressive intentions by other dogs. Aggression between dogs is discussed in more detail in our article Why is My Dog Aggressive to Other Dogs

Does castration stop mounting behaviour?

Mounting behaviour is discussed in more detail in our article Why is my dog mounting other dogs. Where this behaviour is portrayed against female dogs (or in some cases neutered dogs - see above), castration can be very effective.

Mounting behaviour against humans or other objects (e.g. pillows, large fluffy toys) can occur particularly as a dog enters puberty. If this behaviour continues into adulthood, then castration is likely to be recommended and is known to be very successful. If the mounting behaviour is as a result of dominance, other behaviour therapies may also need to be considered.

Does castration eliminate urine marking?

Our article Urine Marking in the house discusses this behaviour in more detail. Castration is known to help in cases urine marking, particularly where the marking is taking place inside the home. On its own, urine marking outside the home is generally not considered sufficient reasoning for castration.

Are there any behavioural side-effects of castration?

It is believed that castrated dogs smell different and can become the focus of attention from other males. This is particularly evident in recently castrated dogs.

Contrary to popular belief, there is no evidence that castration causes a dog to put on weight. It is true that after castration dogs can have an increased appetite and will eat more food if given. Hence the over weight is often due to over feeding rather than the effects of castration.

Castration does not affect an owner’s ability to train their dog. In fact many find castrated dogs are less distracted and easier to train

Any there any alternatives?

Some owners mistakenly believe that allowing their dog to mate will reduce their dog's frustrations and consequently ease behavioural problems. This is not the case and in many cases things can get worse as the dogs interest in females and sense of status increases further.

Hormone treatments prescribed by vets can be beneficial in tackling behaviour problems. They are normally in tablet or injection form and are a useful way of modifying behaviour while other behaviour improvement tactics are employed.

Hormone treatments are also a useful gauge as to the likely effects of castration.