We tend to neuter most dogs in our society although this policy is starting to come under scutiny. In Norway it is now illegal to neuter your dog without a proven reason. The health benefits of spaying female dogs fall in favour of spaying, however, when it comes to male dogs, the health benefits fall in favour of remaining entire.
In the UK we castrate male dogs to successfully prevent unwanted pregnacies but we also castrate for other, often spurious reasons. Even when castration is relevant, there is only a percentage chance that it will work. This varies from 90% for some problems, such as roaming to find potential mates, down to 50% for others such as leg cocking. The male brain is programmed to display male behaviour by testosterone even before birth.
The statistics show that entire male dogs are more likely to show aggression than female dogs or neutered males. Testosterone is implicated in competitive behaviour and entire male dogs are more likely to be competitive over things they value than are either females or neutered males. As a result, they are likely to be more confident in their ability to control things they think are important and are more likely to use aggression when confronted. However, whilst neutering can help with competive, testosterone driven behaviours, once a dog is already acting out these behaviours they become ‘learned’ removing the testosterone won’t necessarily be effective in resolving them.
Neutering is not a staight forward fix-all for male dogs with aggression problems, in fact there is evidence that neutering can increase agression problems if the aggression is motivated by fear because removing testosterone also reduces confidence. It’s now considered advisable not to castrate a dog displaying fear related aggression or other fear related behaviour problems for this reason and accurate diagnosis is therefore essential to determine whether castration is appropriate. It is wise to allow a dog to mature and for his confidence to develop before considering castration. If the accurate diagnosis of a problem shows that castration is likely to help, the chances of success are greatly improved if the operation is done in conjunction with behaviour modification therapy.