Many vets are eager to promote the neutering of dogs, but the pros and cons are not always discussed thoroughly with owners, thus preventing them from making an informed decision about this procedure. Read on to learn about the research-based pros and cons of neutering your dog and how these vary depending on the breed of dog.
Why neuter my dog?
There are many reasons why dog owners make the decision to get their dog or bitch neutered. Usually, the procedure is recommended by our veterinarians in the hope that our beloved dogs will not develop certain diseases later in life, such as testicular cancer, mammary cancer, pyometra and prostate cancer. However, it might not always be the best decision for our dogs in the long run. Recent studies have shown that early neutered dogs have a significantly higher risk of developing other cancers and joint diseases that are more difficult to treat than testicular or mammary cancer. A study of over 40,000 dogs found that ‘neutered male and female dogs were more likely to die from cancer than intact dogs.’ Hoffman JM, Creevy KE, Promislow DEL, 2013.
Other reasons for castrating male dogs or spaying females are more about the owner rather than the dog. Owners want to calm down unruly or aggressive males; castration does not do this, training does! In fact, when neutering male dogs, testosterone-mediated aggression can turn into fear-based aggression; testosterone actually increases a dog’s confidence levels making them feel calmer in certain situations.
Neutering may increase the risk of untreatable cancers like hemangiosarcoma even if it lowers the risk of the more treatable mammary cancer.
Gayle Watkins PhD, avidog.com, 2020
When bitches are in season, they will make a mess in the house and attract unwanted attention when out and about – maybe even finding themselves with a bun (or 6) in the oven. However, for the few weeks of the year a bitch is in season, they can be contained to certain areas of the house or walked on the lead at quiet times of the day. Unfortunately, these things are easier said than done and it depends on your personal situation and breed of your dog as to how difficult this might be.
If I do decide to neuter my dog, when is the best time to do it?
It depends on the breed of your dog when it comes to making decisions about getting them neutered – not all dogs are equal when it comes to this process and veterinarians should not be treating them as such. Read on to find out if your breed is at risk based on the most recent research.
Do the benefits outweigh the risks?
As mentioned above, castration reduces the risk of testicular cancer in male dogs, however, the number of intact (non-castrated) males dying from testicular cancer is below 1% anyway as most cases of this form of cancer are easy to treat. Likewise, spaying bitches reduces the risk of mammary cancer (the most common form of malignant tumours in female dogs) and eliminates the risk of pyometra, but this needs to be performed at the correct time; spaying too early can lead to numerous behavioural problems and issues with growth and development. Similarly, bitches who are neutered late have a higher risk of developing cancer of the blood vessel walls, mast cell tumours, dementia and problems with their weight – cancer statistics are increased with the removal of adult hormones!
Removing these hormones during the neutering of both bitches and dogs, not only leads to a higher chance of developing certain cancers (lymphatic cancer being 3 times more likely in early-neutered males) and behavioural issues, but also impacts on growth and increases the probability of developing musculoskeletal problems – particularly in giant breeds.
A study in 2008 found that neutering was associated with a 3-fold increase in excessive tibial plateau angle, which is linked to cranial cruciate ligament tears/ruptures. A 2009 study stated: the occurrence of lymphoma was found to be higher in spayed females. In addition a 2001 study found the same correlation between spaying females and the development of mast cell tumours. Even as far back as 1985, studies were showing a link between spaying and the occurrence of hemangiosarcoma.
However, these statistics do not apply to all breeds, and when you get your puppy spayed can have a massive impact on the development of these problems – look at the research below to find out more…
The research behind the claims
The most recent research, published by Ben and Lynnette Hart 2020, provides a detailed look at how neutering male and female dogs can have different effects on different breeds and suggests what age is best to carry out the neutering process for each.
The study took place over 15 years and looked at 35 different breeds of dog. The health issues that they focussed on were: lymphoma, mast cell tumour, hemangiosarcoma and osteosarcoma – in the cancer category. They also looked at joint issues including: hip dysplasia, cranial cruciate ligament tear/rupture and elbow dysplasia.
In a nut shell, they found that, for some breeds, neutering may be associated with increased risks of debilitating joint disorders and some cancers. Joint disorders were usually found in neutered larger breeds whereas in small breeds, there was no difference between the intact and neutered groups. However, the data did show that some of the small breeds had a greater risk of some cancers if they had been neutered.
The research also highlighted that, although mammary cancer rates were higher in intact bitches, its occurrence was far less than the 25% currently claimed by veterinarians. In fact, this study found the rate to be as little as 6%.
It is important to remember, the procedure itself is a risk, especially to brachycephalic breeds who do not cope well under anaesthetic and there are many non-surgical approaches to treat ailments associated with intact dogs should they become ill later in life.
Not all breeds should be treated the same
I have picked out 3 of the breeds from the study to compare the cancer and joint statistics, however, you can find the full list of breed comparisons here or take a quick look at the overview sheet below.
Border Collie (399 dogs in study)
No variations in joint problems whether they were neutered or not. Males who were castrated between 6-11 months, had a 13% increased risk of one or more types of cancers included in the study. This was an increased rate of 11% of females spayed at the same age. Only 1% of the intact females developed mammary cancer with 4% developing pyometra. The evidence would suggest that if you are getting your Border Collie neutered, it is best to wait until it is over 1 year of age.
Bulldog (558 dogs in study)
Joint disorders were more common in both male and female dogs who were neutered. 7% of male intact dogs and 5% of intact females developed joint disorders later in life. Conversely, this rose to a rate of 15% for males and 18% for females who were neutered at younger than 6 months. There was no significant increase in specified cancer rates between neutered and intact Bulldogs. The occurrence of mammary cancer was 1% for intact females and 2% for bitches who had been spayed between 2-8 years. The pyometra rate was just 2%. The evidence would suggest that if you choose to neuter your bulldog, it is best to wait until they are physically mature to prevent the risk of joint disorders.
Cocker Spaniel (369 dogs in study)
Joint problems occurred in 1-3% of intact males but that increased to 11% in males who had been neutered before 6 months of age. There was no increase in joint issues in females, spayed or not. 6% of intact males developed one of the cancers studied and this was much the same for males neutered at any age. However, for intact females the incidences of the four cancers being looked at was 0%, rising to 17% for females who were spayed between 1-2 years of age – these were completely made up of mast cell tumours. 11% of the intact females developed mammary cancer and 5% developed pyometra. Therefore, the suggested guidelines for neutering Cocker Spaniels is to castrate males after 6 months and delay the spaying of females until after 2 years.
As you can see, the breed of dog affects if and when to neuter so make sure, when discussing this process with your vet, you ask for the specific figures, pros and cons relating to your own dog.
Where you live affects your ‘neutering’ opinion
The approach to neuter dogs varies depending on which country you live in and indeed which vet you speak to. In the USA, it is common for dogs to be neutered early – before they have had a chance to mature physically and mentally. In Sweden, very few dogs are neutered/spayed with the view that it is an elective surgery on an otherwise healthy animal and is considered mutilation – in fact, until 1988 the operation was illegal unless there was a medical reason for it. Neutering is perceived as unnecessary in both Denmark and Norway too, and these areas are known for their lack of stray dog populations thus proving that neutering is not needed for population control.
With this in mind, owners should have a serious discussion with their veterinarian about the pros and cons of neutering and decide what is best for each dog individually. There are also many options regarding the type of spaying/neutering procedure that can be carried out on dogs – some methods allowing dogs to keep producing adult hormones such as: an ovary sparing spay or vasectomy. Read my ‘Types of Neutering‘ post for more information.