Is it really a good idea to neuter your dog? The question was prompted by a friend after she had taken her spaniel bitch to the vet to have her final puppy injections. “The vet assumed that I would be having her spayed, and even went as far as asking me if I would like to book her in,” my friend told me, adding: “I’ve never had any of my previous dogs neutered, and I’m not convinced that I should do so now.” For many years, routine neutering has been the norm in Britain and, as a result, we have one of the highest proportions of neutered dogs of anywhere in the world: about 80%. In the USA, it’s about 83% for male dogs but lower for bitches. Intriguingly, routine neutering is banned in some European countries. The Norwegian Animal Welfare Act, for example, rules that surgical procedures are not to be used to adapt animals to the needs of humans, unless strictly necessary. (Read: Inbreeding and line-breeding in working dogs.)

Deciding whether to neuter your dog

There are, of course, numerous perceived advantages of neutering, of which the most obvious are the prevention of accidental pregnancies leading to unwanted puppies, and making male dogs better behaved and less likely to roam. Another is that early neutering allows breeders to prevent their bloodlines being used by rival breeders: some send puppies to new homes already neutered at only eight weeks old. Such early neutering can lead to a host of problems, ranging from allergies to developmental growth, and can also make individual animals aggressive and untrainable.

However, neutering older dogs also brings risks that vets seldom discuss with their clients. One of the most common assumptions is that neutered dogs are better behaved. However, the most frequently observed behavioural issue with spayed bitches is fearful or submissive behaviour, while for dogs it is aggression, which, ironically, is the very reason why many dogs are castrated in the first place. One often seen effect of neutering is the dog losing its identity, which can lead to a marked change in how it reacts to its companions or even other dogs it meets while being exercised or worked.

Little research has been done on the dog’s mental, rather than physical, state after neutering but there’s evidence to suggest that some dogs when neutered early (before the age of two) become adult-sized animals locked into a state of permanent puppyhood. The truth is that there’s no guarantee what the long-term impact on your dog will be after the operation. (Read: alternative gundogs .)

Neutered golden retrievers can be more likely to suffer hypothyroidism

With bitches, the most obvious benefit of spaying is a marked decrease in mammary tumours but even this might not be true, as the original study was made many years ago (1969) and is no longer regarded as entirely sound. A problem with spayed bitches is a much greater likelihood of incontinence, although this varies from breed to breed. Analysis showed that 34% of Irish setters suffered incontinence after being spayed but only 6.8% of springers, 3.2% of labradors and 2% of cockers.

Research into several thousand golden retrievers showed that neutered individuals were more likely to develop an underactive thyroid (hypothyroidism), particularly those dogs that were neutered when puppies. Hypothyroidism can lead to numerous other problems, ranging from lethargy to a slow heart rate and skin infections. There is evidence that dogs suffering from this condition are much more difficult to train. Rupture of the canine cranial cruciate ligament is one of the most common orthopaedic problems seen in veterinary practice around the world, and there is increasing proof that early neutering may affect the development of the tibia and other long bones in a dog.

There are a number of positives from neutering. With dogs, castration does reduce the risk of prostate problems later in life, albeit even neutered dogs can suffer, and it also rules out testicular cancer (although this is a comparatively rare condition). It certainly stops dogs roaming in search of bitches, and I have also heard handlers claim neutered picking-up dogs are more likely to concentrate on their job rather than checking for bitches in heat.

Phantom pregnancies

Bitches have an uncanny knack of coming on heat when you don’t want them to, typically at the peak of the shooting season, so spaying is a way of avoiding this. This also stops phantom pregnancies. I had an unspayed springer bitch that suffered from phantom pregnancies, sometimes leading to mastitis. With hindsight, I should really have had her spayed. Another unspayed bitch of mine suffered from pyometra at the age of 13. Fortunately, we noticed her condition early; she had a hysterectomy and made a complete recovery.

I’ve only ever had one of my dogs neutered. She was spayed at the age of four when she developed mammary tumours that proved to be benign. She lived to be more than 16, and was active to the end. I’ve often wondered how much being spayed contributed to her longevity. I would never rule out neutering a dog of mine but I would think carefully before doing so. Sadly, most neutering is done for the convenience of the owner, not the health of the dog, which is the wrong way round.