“Jein” was the unexpected answer to a question posed at a BVA Congress session at the London Vet Show: “Is neutering dogs doing more harm than good?” A colloquial expression used by Germans which combines their words for “yes” and “no”, “jein” is an ideal response to a client seeking advice on whether a male dog should be surgically neutered, according to veterinary behaviourist Sarah Heath.
Sarah said there is no simple answer to this query, as the appropriate guidance will depend on a thorough knowledge of the owner, their pet and their home environment. But she does believe that the policy of routinely neutering male and female dogs, which in recent times has become the norm in the UK, should be reconsidered.
There is strong evidence that these procedures will increase the risk that the patient could develop a wide range of medical conditions, especially when conducted before they reach skeletal maturity. Moreover, surgically removing the gonads is not a panacea for behavioural issues (such as aggression) in dogs and can actually have detrimental effects on the animal’s behaviour. Furthermore, while chemical castration methods have the advantage of being reversible, there are still many questions on their long-term impact, particularly on the animal’s behaviour, she said.
There is strong evidence that [neutering] procedures will increase the risk that the patient could develop a wide range of medical conditions, especially when conducted before they reach skeletal maturity
Professor Michelle Kutzler of Oregon State University is an internationally renowned authority on reproduction in companion animals. She said that surgical neutering has proved a valuable tool for improving canine welfare over the years. She observed that by 2020, the number of unwanted dogs euthanised each year by humane societies in the United States had fallen by 97 percent from its peak in the early 1970s as a result of neutering becoming more widely practised.
But while neutering is an effective cure for unwanted pregnancies, the resulting fall in sex hormones causes a significant rise in circulating luteinising hormone (LH), which influences the function of the many tissues known to express LH receptors, said Michelle. This appears to be the mechanism through which neutering has now been shown to increase the risks of developing certain cancers, various orthopaedic conditions (such as cruciate ligament rupture), urinary incontinence and endocrine dysfunction.
Surgical neutering has also been shown to exacerbate behavioural problems such as anxiety in Vizlas and reactivity (aggression) in German Shepherds, Sarah pointed out. Other studies suggest that waiting until after the animal reaches puberty can reduce the chances of the dog showing signs of fearfulness in later life. Hence, it is important for owners and their veterinary advisors to discuss the health and behavioural impact of neutering, especially when the proportion of dogs neutered in the UK is so high – at 70 percent. This is a significantly greater number than in most other European states, and the procedure is illegal in Norway, for example, except for specific medical reasons.
Waiting until after the animal reaches puberty can reduce the chances of the dog showing signs of fearfulness in later life
In prescribing the gonadotrophin-releasing hormone analogue Suprelorin, UK veterinarians do have a medical option for suppressing fertility and sexual behaviour in male dogs. Dr Neil Mottram, technical manager for the manufacturer Virbac, believed that many clients have concerns about the effects of their dogs being surgically castrated and that huge numbers of dog owners would welcome a reversible method. He argued that all clients should be offered the choice of giving their dogs the hormonal implant.
Veterinary nurse Nicola Lakeman recognised that this would require changes in the work patterns of small animal practices. Controlling fertility is a complex issue and should be discussed at length during a pre-neutering consultation. Obtaining informed consent is essential in these circumstances, and the conversation should never take place on the morning of the scheduled procedure. It is also vital that this discussion should take place between the owner and their veterinary surgeon or nurse who have received additional training in reproductive medicine and fully understand the issues involved, she said.
Obtaining informed consent is essential in these circumstances, and the conversation should never take place on the morning of the scheduled procedure
Suprelorin was first licensed for preventing unwanted matings in dogs in Australia in 2001, pointed out Michelle, and so it is not a new product. This means there should be data available on its safety and efficacy in routine use. If the drug has been regularly causing the sort of issues that are now known to occur with surgical castration, she was sure that “there would be some evidence of this in the form of angry telephone calls to the manufacturers”. However, the drug is not licensed in the US, and her research group, which has been focused on companion animal reproduction for many years, has no data on the clinical value of the product. She urged her UK colleagues to scour their clinical records to answer some of the unanswered questions about the long-term effects of hormonal implants in dogs.
There is some experimental data showing that suppressing LH can reduce aggression in rats and clinical evidence for the reversal of incontinence in female dogs. But until more is known about this drug, it would be premature to recommend it as a prophylactic treatment for the health issues seen in surgically neutered dogs. The one exception would be in large-breed dogs that have already experienced a cruciate ligament rupture. Offering the LH suppressor might be prudent when about 50 percent of dogs will have lesions in the contralateral limb within one year of the initial injury, she warned.
