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Sterilisation – Is it always a matter of course?

We regularly get questions from our clients when their dogs reach 6 months of age, as to whether they should now spay or neuter them. Most of the time there is some confusion as to the right course of action and people are looking for some clarification on the many things they have heard from vets, welfare associations, friends and family. There are so many strong opinions on the subject and it is interesting to note that in some European countries it is illegal to remove the sex organs of a healthy dog, while in contrast 90% of dogs in the US are sterilised.

In a country like South Africa, where we have a very serious problem with overpopulation of dogs and cats - many of these animals coming from areas gripped by poverty and lack of education - sterilisation is a priority for most welfare organisations. Chatting to a colleague recently who manages a local rescue organisation, I was pleased to hear that she is seeing a decline in puppy and kitten numbers in the local communities as a result of their sterilisation campaigns and the relationships they have formed with the people who now actively bring their animals for sterilisation, rather than the unwanted pups or kittens.

While there is no doubt at all that in the context described above, sterilisation is absolutely the best course of action, we have to concede that not all dogs are living in this kind of situation and what may be the best course of action for “general welfare” i.e. reducing the number of unwanted pets that end up in shelters, is not necessarily the best course of action for an individual dog in very different circumstances.

While apparent health and behaviour benefits of sterilisation are quickly put forward in an attempt to persuade reluctant owners to spay or castrate at 6 months of age, the reality is that there are actually pros AND cons to sterilisation. From a health point of view, while it is true that sterilisation may reduce the likelihood of mammary tumours and negates the risk of pyometra in bitches and testicular tumours in dogs, a study of golden retrievers indicated a clear increase in the risk for developing other types of cancers, such as lymphosarcoma, hemangiosarcoma and mast cell tumours in early-sterilised dogs (before 12 months of age). There was also an increased likelihood of joint problems, such as hip dysplasia and cranial cruciate ligament tears: Similarly, a study of Rottweilers indicated that the earlier they were sterilised, the greater the risk for developing osteosarcoma:

From a behaviour point of view, things are just as complicated. While it is commonly advised that castration prevents or reduces aggression and other behaviour problems, the statistics do not reflect this and neither does our understanding of the motivations for behaviour support this. In fact, one study summarises: “Among the findings, neutered dogs were more aggressive, fearful, excitable, and less trainable than intact dogs”.

When one looks at the motivations for aggression, we need to understand that testosterone does not cause aggression. The most prevalent motivation for aggression in the average pet dog is fear and insecurity. This may be as a result of trauma or as a result of lack of socialisation, but most aggression that we see, is a direct result of a dog perceiving a threat and using the “fight” response to deal with it. The biggest predictor for an aggressive adult dog, is a fearful puppy. In order to try to prevent a fearful or insecure puppy from developing into an aggressive adult, we do EVERYTHING in our power in INCREASE the puppy’s confidence – and guess what, that is exactly what testosterone does. The rise in testosterone in adolescence will embolden a young dog and can be very useful for helping him to overcome insecurity. The worst thing that one could do to a fearful puppy is castrate him at 6 months of age.

On the other hand, inter-male aggression i.e. when a male dog regularly looks for fights ONLY with other intact male dogs is said to respond to castration with a 60% success rate: Although keeping them away from other intact males for a period of time and allowing them to have healthy social interactions with other dogs may also break the habit in some cases.

Bitches are a little more complicated: while hormonal changes associated with the female heat cycle can involve increased risk of conflict with other bitches, it has been noted that bitches that display aggression towards their owners, tended to display even more aggression towards their owners after sterilisation:

Of course one always has to consider whether with better knowledge and handling skills on the owners’ part, such a problem could have been managed better or prevented altogether, especially since the label given to the aggression described here, is highly questionable.

In my own experience, bitches tend to become less active after a season, which is possibly where the idea of allowing a bitch to have a season to “calm her down” has come from. What people neglect to add, is that once the heightened post-season progesterone goes back to normal levels two months later, the bitch usually becomes just as active as before. At this time, many bitches will also experience a phantom parturition and start to nest (scrunch up blankets or dig holes under bushes) and “mother” toys. They may also become more anxious about “intruders” around the home environment, as though they were guarding a litter.

So, what is the point of all this and what conclusions can we draw? Should we sterilise our dogs and if so, when?

Well, I would say the answer is – IT DEPENDS….

The first factor to consider is whether you are able to prevent your dog from mating with another dog or not. Clearly, if your dog is not secure on your property or with you AT ALL TIMES when out on walks, then the ONLY responsible course of action is STERILISE to prevent unwanted pregnancy. That trumps everything else.

However, if you are a responsible owner and are able to manage your dog to prevent them mating randomly with other dogs in your home (obviously more than one intact pet is a complication you need to consider) or off your property, then I would suggest you consider the following:

1. Your dog’s size – small dogs mature a lot faster than big dogs and are at less risk for joint problems. The risk implications for early sterilisation from a joint health point of view are far greater for big dogs than small dogs.

2. Your dog’s breed – What many of the studies have shown is that certain breeds are more susceptible to certain types of health issues and will be more affected than others by early sterilisation. If your dog is in one of these high-risk groups, then delaying sterilisation may be something to consider. A case in point would be Dachshunds, as although they are a small breed, there is a study that has shown an increase in incidents of invertebral disc disease in early spayed and castrated dogs:

3. Your dog’s temperament and behaviour – If your dog is reactive because he is anxious, insecure or fearful, do not think that castration is going to make him less reactive, because it won’t. If your dog seems to be “enjoying” a good scrap with other intact males, then some urgent management is needed, but castration may not go amiss.

4. Your dog’s history and current emotional state – I have several clients with rescued dogs who I have advised NOT to sterilise (particularly bitches) purely because I felt that at that time in their lives, the actual veterinary experience would be traumatic for them and would hamper their recovery from past trauma. In those cases, the rescue organisation has given the owners permission to wait for the dog to settle and gain more confidence, before they underwent the procedure and in all cases the results have shown that it was absolutely the right thing to do. Obviously, there has to be enormous trust between the organisation and owner, but one would argue that homing a dog in such a precarious emotional state would imply enormous trust on behalf of the organisation in that owner in the first place.

So, there are really no simple answers and one has to evaluate all the pros and cons for each individual dog, based on their circumstances and needs. For responsible owners, delaying sterilisation until physical maturity (when the growth plates close at around 18 months) is a very valid option. Just this delay can mitigate some of the negative effects of early sterilisation, while preventing long term complications of not sterilising at all.

Photo: Cruz, still in possession of is testicles


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