by Lynn Broom.

Longmead Veterinary Practice
Pet dogs kept in family houses are often castrated to enable them to be more acceptable companions and to reduce the risks to their health both from wandering and from certain age related illness. But it isn’t right for all dogs.
When I graduated 22 years ago, the general advice was to castrate your pet dog unless you intended to breed from them. We are aware now that there are certain reasons why this may no longer be the recommendation.
Certain breeds are at an increased risk of developing cancer if they are neutered before they are physically mature. Rottweillers, for example, have a significantly increased risk of developing bone cancer if neutered before one year of age. Dachshunds have a higher risk of intervertebral disc disease (slipped disc) if neutered, and this risk further increases if they are neutered early. It is, therefore, now recommended that large breed dogs are not neutered before they are 15 months old and dachshunds not before 12 months.
However, if you have a large dog that needs neutering earlier because of management or behavioural issues, you will need to weigh up the balance of benefits with your vet. Earlier neutering should be carried out if necessary.
Currently, early neutering doesn’t appear to pose an increased health risk to most small breeds. Terriers especially are often quite ‘sexually active’ from a young age, so neutering before puberty can make them much more enjoyable to live with!
Male dogs suffering from anxiety may be made worse by neutering. Testosterone gives them extra confidence, so castration may make this anxiety worse. It’s vital to understand the reason behind aggressive behaviour before deciding whether to neuter. Anxious dogs can show fear-related aggression, which may be mistaken for dominance aggression associated with male hormones. Assistance from a behaviourist will help resolve the anxiety before proceeding with castration.
Many male behaviours are learnt behaviours – scent marking and interest in in-season bitches, for example, are unlikely to be lost after neutering. Dogs that have a strong play drive are unlikely to change after castration, although dogs wandering to find a bitch will probably improve.
An alternative to immediate surgery is an implant that simulates all the effects of castration but only lasts approximately six months. This allows the assessment of any effects without the irreversible consequences of surgery. Repeated implants or progressing to surgical castration are then options if the effects are beneficial. Implants may also be used in cases where surgery or an anaesthetic carry additional risks – for older dogs, for example.
The health effects of castration can be multiple. Older entire male dogs are commonly affected by an enlarged prostate, which can cause difficulty urinating and defecating – this is reversed by castration. Benign anal ademonas can form on the anus and these will resolve following castration. Testicular tumours are avoided by castration. Dogs with a retained testicle generally benefit from castration to prevent them passing on this genetic defect and to prevent the retained testicle becoming cancerous or twisted.
Uncommon risks of castration are prostate tumours and urinary incontinence and potential for weight gain. If you need help deciding whether castration is right for your dog, your vet will be happy to advise based on the dog’s breed, age, health issues and behavioural problems.