Castration of male dogs involves the removal of both testicles via one incision in front of the scrotum. The scrotum itself is not removed during the surgery, but will gradually get smaller over time. Removal of the testicles causes testosterone (male hormone) levels to fall significantly, and often has an effect on their behaviour as a result.


  • Can reduce the risk of straying with the associated risk of road traffic accidents.
  • Can reduce unwanted sexual behaviours such as urine marking.
  • Can reduce aggression towards other dogs although there is no clear evidence to support this in literature.
  • Eliminates the risk of testicular cancer (often of low mortality rate).
  • Reduces the risk of developing benign prostatic hypertrophy (BPH), this is a non cancerous enlargement of the prostate which can lead to difficulty urinating and defecating. Dogs with BPH are also at increased risk of developing prostate infections and abscesses which can be persistent and difficult to treat.
  • Reduced risk of developing perianal tumours and hernias.


  • There is always a risk of adverse reactions with any general anaesthetic or surgery, this can include death but this risk is very low, on the contrary most recover remarkably well.
  • Some specific risks of castration include haemorrhage, break down of the wound, suture material reactions, bruising, inflammation and infection of the wound. Unfortunately, post-operative complications such as bruising, inflammation and infection are much more likely in animals than humans undergoing the same procedure – our involvement to try to keep them calm and stop wound interference will go a long way to reduce these risks.
  • An association with an increased tendency to gain weight.
  • Neutering of a nervous dog can be detrimental to their behaviour, it may be recommended that you see our behaviourist, Andrew Hale, prior to neutering to discuss this. It is also possible to ‘chemically’ castrate via the use of a short acting implant injected under the skin in order to test their response to the reduction of male hormones.
  • Early castration of large breed dogs may affect their growth and have an effect on joint health when they are older; there is some evidence to show this may be true for Retriever breeds for example. Castration after a year is an option for larger breeds, although we do need more research to quantify this risk more firmly.
  • Can cause coat changes.
  • Increased risk of developing prostate cancer compared to entire dogs

A note on retained testicles (Cryptorchidism)…

Cryptorchidism is the failure of one or both testicles to descend into the scrotum. It can be inherited if the dog is used for breeding. Castration is strongly recommended in theses cases as a retained testicle is up to thirteen times more likely to develop cancer. If the testicles have not descended by 6 months of age, they are unlikely to in the future.

The procedure is more complicated than a standard castration as the retained testicle can be anywhere from just in front of the scrotum to internally by the kidney. This means the surgery can take significantly longer and cost more than a standard castration. There is also an increased risk of post-operative complications especially if an abdominal incision is needed. If you have any further questions, please book an appointment to discuss the procedure with a vet or vet nurse.

Pre-operative care

Please make sure your dog has not had any access to food after 8pm the previous evening, water can be left down until approximately 7.30am on the morning of the surgery. Please take your dog for a short walk in the morning as this will allow him to go to the toilet. It is not a good idea to tire him too much as he will have a big day ahead of him. Please make sure his coat is as clean as possible as this will reduce the chance of infection. If your dog has any dietary requirements it is a good idea to bring his own food in for his lunch. Please let us know if your dog has any behavioural concerns that may affect his/our wellbeing whilst he is with us.

Admission for surgery

On arrival at the surgery, you can expect to be seen by a vet or a vet nurse who will check that you understand the nature of the operation and will examine your dog to look for any signs of being unwell or of cryptorchidism. They will ask you to read and to sign a consent form for the procedure and ask you to supply contact phone numbers. Although we do not expect any trouble, it is very important that we can contact you in case of an emergency during the day so please keep a phone at hand.

Post-operative care

Dogs usually recover quickly from the surgery. Post-operative pain relief and two post-operative checks are included in the cost of the procedure.

It may be necessary for your dog to either wear a collar or a pet t-shirt to stop them licking at the wound as it heals. If your dog is allowed to lick the area, they may pull out sutures or cause inflammation and or infection. Please discuss your preference between shirt and collar with your vet or vet nurse on the day of the procedure.

It is important to monitor him closely for 24 hours following the procedure. Some dogs will require further monitoring depending on their individual reaction to the general anaesthetic/procedure. Please be aware of this when booking a date for his castration. You will be given a post operation care sheet to guide you through this process and you will be given a dedicated discharge slot in order to discuss any questions or concerns prior to taking him home.