Chemical castration vs surgical castration – Which is best?


Chemical castration vs surgical castration – Which is best?

There are 3 main reasons to neuter your dog

  1. To prevent accidental litters/mating; there is a huge excess of homeless/unwanted dogs in shelters and foster homes. The canine population is over subscribed. By reducing the number of breeding dogs and accidental litters we are also reducing the problem.
  • To prevent testosterone related conditions/ illnesses, such as;
  • Aggression
  • Urine marking
  • Sexual behaviour
  • Prostate disease, such benign prostatic hyperplasia
  • Testicular and anal cancer; 1 in 3 intact male dogs develop one or more testicular tumour
  • To prevent the passing of hereditary and breed-related conditions or illnesses.

In recent studies, castrating male dogs has proven to extend their life expectancy by ~14%

In a small number studies, one of the few downsides to neutering your dog is that in some cases where the individual suffers with high levels of stress or anxiety, the reduction in testosterone can result in “fear aggression”.

There is ongoing research into the involvement of testosterone in bone development and maturity. We consider each patient on a case by case basis, in relation to their breed, age and development. 

Chemical castration

  • Chemical castration involves placing a Suprelorlin (deslorelin) implant into the subdermal layer of the skin which tricks the brain into reducing serum testosterone levels
  • The implant duration usually lasts from 6-12 months, although it can vary in individuals
  • Infertility is achieved from 6 weeks after insertion
  • The ability for dogs to sire offspring following return to their normal testosterone levels, has not been investigated, however testosterone levels in >80% dogs using the implant returned to normal levels within 12 months and  98% returned to normal levels within 18 months.
  • As the implant wears off, it can be costly to replace them over time

Surgical castration

  • This involves the patient going under general anaesthetic (so he doesn’t feel anything) and removing the testicles surgically.
  • Most of the testosterone present in the body is made from the testicles, without them, levels rapidly decline.  
  • It is a permanent procedure.
  • Potential post-operative complications include; wound-breakdown or infection, swelling (seroma) or bleeding. However, this is a routine procedure in most general practices and so has a low complication rate. Although it’s important to appreciate that general anaesthetic carries its own risks
  • Recovery time is usually ~7 days. He will need to wear a buster collar on to ensure he doesn’t lick the wound and result in any breakdown or infection. Exercise restriction ideally for ~5 days after the operation to prevent any stiches breaking down.  Overall in my opinion, dogs handle the procedure really well. With my own dog he was trying to get up to his usual mishaps within 24-48 hours!


Essentially the main difference between chemical and surgical castration is that chemical is reversible and so if any unwanted side effects occur such as fear aggression then they can be reversed. However, as mentioned before it is costly to maintain the implants. There is also less studies on the reduction in risk of testosterone related diseases with the chemical implant compared to surgical castration.

In either case, come in and talk to one of our vets who will be happy to help guide you in your decision!

My own newfie, Big Bear!

Dr Martine McCann, BVMS, MRCVS



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