Is surgical castration right for every dog?

Many dogs are now castrated using a slow release implant, which results in temporary and reversible castration

02 November 2020, at 7:50am

The castration of dogs in the UK has been a common elective surgical procedure for many years with 70 percent of the UK’s dog population estimated to be castrated (CEESA, 2018). Castration and bitch spaying are viewed, along with vaccination and parasite control, as one of the mainstays of preventative healthcare. But is this the right choice for every dog, or the only choice?

Pet owners generally opt for castration on the advice of their vet in order to stop unwanted breeding and to improve prospects for health and behaviour, but surgical castration is irreversible and may not always achieve desirable results for the pet or the pet owner.

The practice of routine surgical castration in the UK, USA and Australia contrasts markedly with other European countries. In Norway, for example, it is illegal to castrate dogs under the Norwegian Animal Welfare Act unless it is deemed medically necessary or for the welfare of the individual pet. Whilst 70 percent of UK dogs are castrated, the castration rate is just 39 percent in France, 40 percent in Spain, 32 per­cent in Italy and 52 percent in Germany (CEESA, 2018).

The subject of surgical castration presents a dilemma for many pet owners. In a recent survey, 46 percent of pet owners stated they felt guilt after opting for the surgical procedure because they consider surgical castration to be a traumatic experience for their pet, and 22 percent of dog owners stated they felt regret (Harris interactive, 2017). Whether the owner is trying to prevent unwanted litters, or to moderate behaviour, surgically removing a part of their dog can feel like a huge decision to make.

Permanent neutering may not always be wanted or needed and castration can have undesirable effects in some pets, such as coat or behavioural changes and a tendency to gain weight. The testes are necessary endocrine glands for nor­mal metabolic, musculoskeletal, behavioural and anti-neoplastic health. Whether surgical castration is really in the best interest of the pets has raised the concerns of many vets and owners. Although it may seem that spaying and neutering is the respon­sible choice for most pets, active research continues to examine the long-term health implications.

So, what do our European neighbours do? As an alter­native, many dogs are now castrated using a slow release implant which contains the active ingredient deslorelin, which results in temporary and reversible castration. The implant has been prescribed by vets as a licensed medicine for more than 12 years in Europe and is licensed for the induction of temporary infertility in healthy, entire, sexually mature male dogs. This offers both vets and owners an alternative to surgical castration, conferring the benefits of neutering without the permanency. This can be helpful in sit­uations where owners wish to “try before they buy” in order to see how their dog would behave once castrated, or if they only wish for temporary effects.

The deslorelin implant is placed under the skin, usually in the scruff, using a device similar to a microchip implanter and it slowly releases a hormone which acts on the dog’s pituitary gland. This is what produces the hormones that stimulate the testes (or ovaries in the bitch) to produce the sex hormones and hence controls fertility.

In male dogs, deslorelin initially stimulates this gland but, after just two weeks, the gland stops production of the hormones that control the testes; after a couple of weeks the testosterone level is very low and comparable to a surgically castrated dog. As there are no other hormonal effects, this produces a true castration without any other complications.

The lowered testosterone levels result in reduced semen volume, sperm production and motility with increased sperm abnormalities. A reduction in libido is also seen, though it is important to note that a lack of testosterone does not always lead to complete absence of mating behaviour.

Infertility can take up to eight weeks to develop but, if the implants are renewed, castration can be maintained. Owners can assess the behavioural and physical changes of an implanted dog with the option to revert at a later date if longer-term castration is undesirable. This true comparison can help owners to assess the benefits of castration.

Author Year Title
CEESA 2018 Pet owners and their pets [internal market research]
Hart, B., Hart, L., Thigpen, A. and Willits, N. 2020 Assisting decision-making on age of neutering for 35 breeds of dogs: associated joint disorders, cancers, and urinary incontinence. Frontiers in Veterinary Science, 7
Harris interactive 2017 Understanding the usages and attitudes around cats and dogs sterilization and evaluating the potential of Suprelorin [internal market research]

Technical Director at Virbac

Alex Allen, BVM&S, MRCVS, qualified from Edinburgh University in 1998 and worked in small animal practice for several years. He now works for Virbac as Technical Director. In this role, Alex oversees and provides technical and regulatory support on using Virbac products.

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