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Neutering pros and cons

Is it wise to neuter? It’s legal from 10 weeks old.

Our wish is that people will have all the relevant academic and veterinary evidence so that they are able to make up their own minds. So here are the pros and cons of neutering for an informed choice.

otis weave

Opinion and fact can be easily muddled. Like most controversial topics.

We concentrate here on the facts. I’ve included references.. People can check up and if they wish, do further reading. Where I offer my own thoughts, I have used this colour text.

It is illegal to neuter in some Scandinavian countries.

They say it creates more problems than it solves. This surprises us here in the UK, what we’re told is very different. Vets and behaviourists cannot agree whether it’s sensible to neuter British dogs, and if so, when would be the best time.


Pressure to neuter increased from the USA, because strays were a huge problem. In contrast, US pet culture is very different, presumably due to large predatory wildlife. Cats live inside and dogs outside. As a result, a considerable number of dogs were able to escape or roam free. Inevitably, many ended up with puppies. Strays were a big problem in the 70’s. 24 million abandoned or stray US pets were killed per year.

Persuasive campaigns successfully encouraged neutering as the responsible thing to do. By 2007 there was significantly fewer strays. Killing was reduced to 4 million (per year). There is obviously still some way to go, but this is a vast improvement. It was an effective solution to a national crisis. With the moral emphasis on adopting from shelters, it is interesting to see that in 2010, there was significantly fewer new puppies registered with the American Kennel Club. In contrast, here in the UK, the KC contract has safeguards preventing dogs from going into a shelter. Rehoming is the breeders responsibility.

Dogs don’t live in the garden in the UK. They’re based inside, but cats are free to roam outside. This is the exact opposite to the US- so our stray dog population wasn’t such a problem. Unfortunately campaigners failed to realise our local difference. Neutering was also aggressively promoted as sensible and responsible here. Unsurprisingly it caught on. Ideas sprang up about the supposed benefits and were readily accepted in the public mind- understandably, people were keen to find easy solutions to annoying habits.

Opinions and facts with neutering pros and cons

It was widely believed that neutering stops humping, makes dogs healthier, more compliant, less aggressive… However, more facts became available as new studies were done and things are not as clear cut as it seemed. And now, there is a growing weight of evidence shows that neutering can seriously negatively effect the health and well-being of our best furry friends. 

Nothing has changed and that’s alarming. Neutering is expected and encouraged. Our stray population is minimal so why are the supposed benefits still doing the rounds? Why quietly ignore the facts?

What we in the UK need to consider is why risk behavioural and health issues to neuter a dog who never gets an opportunity to roam around freely and produce puppies. A thing my Dad was fond of saying was “if it ain’t broke, don’t fix it”.

Let’s look at facts to compare neutering pros and cons.

1) Neutering to stop unwanted pregnancies:

Did you know there is a canine male contraceptive implant- as well as the equivalent to the “morning after pill?

The most obvious benefit to neutering is that it will save unwanted pregnancies. This is important for households where there are a few dogs, where it is difficult to separate the girls when they’re in season. It’s obviously sensible to neuter cats, who go out and about independently. 

But what of the single dog from a “normal” loving  family? The pets aren’t roaming around on their own as their family is conscientious and wants the best for them? Is it sensible to neuter that animal?

2) Neutering to “control behaviour”.

Neutering halts mental development. People thought that permanently juvenile dogs made more compliant pets. However, we now understand that neutering causes more behavioural problems than it solves. Studies by the American Kennel Club Canine Health Foundation (AKCCHF) have shown more behavioural problems become apparent when a pet is neutered, and that the earlier the neutering, the more behavioural problems are reported. It makes sense that a dog with a fully matured brain will be able to think things through better than their (comparatively) immature counterparts.

It is more likely that neutered dogs will hump or show undesirable sexual behaviour, the AKCCHF studies found. Humping (or twerking as we now call it) is usually down to habit. [Info on how we manage the behaviour further down the page.] 

Neutering can cause and exacerbate aggression. Neutered dogs are more likely to have noise phobias and be anxious or aggressive, the AKCCHF studies found. The rise in aggression corresponds with neutering under one year old in females. However, the insecurity from the loss in testosterone effects male dogs of all ages, increasing the chance of aggression. (Please note that it is very rare that we see a “properly” aggressive dog, who would attack with little cause or warning).

Norwegian attitudes are very different as American campaigns had little impact. The Norwegian Animal Welfare Act states that neutering can only be done when medically necessary. Torunn Knævelsrud, head of Section for Animal Welfare and Fish Health at the Norwegian Food Safety Authority (NFSA) says “neutering can never be a substitute for proper training”.

If you are thinking of neutering to control behaviour, the weight of evidence seems to point to leaving them intact and the advice urges us to consider other options. 

3) Neutering cons- growth problems

Dogs who are neutered when they were young- before or during puberty- tend to be larger than their entire siblings as early neutering causes a delay in the closure of bone growth plates. Growing and maturing relies on sex hormones and process is severely disrupted by neutering– making overall bone structure lighter and their chests and skulls narrower. Body proportions change. Weight distribution becomes abnormal as a result. This causes ligament and joint issues, most frequently in the legs and hips. Vet Mark Elliott’s practice does not offer early neutering. He says that supplements for osteoporosis help those whose neutering altered their bone density..

4) Surgery Risks

As with any medical or veterinary procedure, there are risks from the procedure itself- from the anaesthetic or infection for example.

Data is extremely variable. The danger being somewhere between 1 and 24% for all complications, between 1 to 4% for severe complications. 1 In 1,000 dogs die from the surgery and some reports are higher for puppy (pre-pubescent) neutering. The difference in chance depends on the skill and experience of the individual vet or practise, I assume.

Did you know that it’s cheaper and easier to neuter younger animals- they need less anaesthetic?

Some vet practises offer discounts and encourage early neutering. I fear they may be thinking more about their pockets than the welfare of the animals under their care. And that’s very scary.

5) Health pros and cons.

Please read this and make up your own mind as to what is best for your dog.

Pros to neutering to male dogs (health)

  1. Castration reduces the less than 1% chance of testicular cancer to zero.
  2. There’s a reduction in the slim chance of non-cancerous prostate problems.
  3. Male dogs have less chance of acquiring a perianal fistula (a rare but nasty problem, effecting mostly GSD in middle age).
  4. There is some (inconclusive atm) data that suggests there may be a reduction in diabetes.

Cons of neutering to male dogs (health)

  1. There is a significant increased risk of Osteocarcinoma (bone cancer), providing the procedure is done before the dog is one year old. It’s more common in medium/ large breeds and the prognosis is very poor.
  2. Cases of cardiac hemangiosarcoma (a nasty rapid growing cancer of the heart) increase by 1.6%.
  3. The risk of hypothyroidism (under active thyroid) increases by 300%.
  4. Progressive geriatric cognitive impairment is more likely.
  5. Obesity increases (300%).
  6. The (0.6%) chance of prostate cancer is increased by 400%
  7. The occurrence of urinary tract cancers (less than 1% in intact dogs) went up by 200%.
  8. Hip dysplasia doubled and risk of orthopaedic disorders is significantly increased.
  9. The chance of a cranial cruciate ligament tear increases from 0.0? to 5% in early-neutered males.
  10. Increased risk of adverse reactions to vaccinations.
  11. Almost 10 percent of early-neutered males were diagnosed with lymphosarcoma (cancer in the blood). It’s 3 times more likely.

Pros of neutering to female dogs (health)

  1. The situation is more complex, as risks of various health problems are different between different breeds.
  2. Overall, neutering reduces the (1%) risk of pyrometa (serious uterine infection).
  3. It cancels out the (less than) 0.5% risk of uterine, ovarian or cervical cancer.
  4. There is less chance of acquiring a perianal fistula (a rare but nasty problem, effecting mostly GSD in middle age).
  5. The risk of mammary tumours is reduced (if done before 2.5 years old).

Cons of neutering to female dogs (health)

  1. “Spay incontinence” is the inability to control the bladder due to the operation. It is caused in 4 – 20% of female dogs.
  2. The risk of a recessed vulva, of vaginal dermatitis and vaginitis is significantly increased, especially if the procedure is done before puberty.
  3. There is a significant increased risk of Osteocarcinoma (bone cancer) if the procedure is done before the dog is one year old. It’s more common in medium/ large breeds and the prognosis is very poor.
  4. Spaying increases the risk of splenic hemangiosarcoma (a nasty rapid growing cancer of the spleen) by 220%.
  5. Cases of cardiac hemangiosarcoma (a cancer of the heart) went up by (just under) 500%. This caused the deaths of 8% percent of the girls who were neutered after their first birthday.
  6. The risk of mast cell tumour increases from 0.0? to 6% in females who were neutered after 12 months.
  7. The risk of an under-active thyroid is tripled.
  8. Cases of obesity increased by 300%.
  9. The risk of persistent urinary tract infections increased by (around) 350%.
  10. Neutering doubles the small risk (less than 1%) of urinary tract tumours.
  11. Risk of orthopaedic disorders significantly increased. Hip dysplasia doubles.
  12. The chance of a cranial cruciate ligament tear increases from 0.0? to 8% (in early-neutered girls).
  13. Increased risk of adverse reactions to vaccinations.

With all of this evidence, why on earth don’t vets also offer people a choice of vasectomies/ tube ties instead? Dogs would be able to keep their hormone producing organs!

Who wouldn’t mind paying a little extra, if that what it takes….

I don’t understand why the regular neutering operation is full removal and complete hysterectomy. Vasectomies and tube ties would ease many of the health problems. The hormones so important for proper growth and maturity would still be present. I can understand why it could be tricky for tiny dogs, but neither myself or Google could come up with a logical answer why it shouldn’t be routine for medium and larger breeds. It’s got to be more kind.

If you ask your vet, please let me know what they said

Neutering pros and cons: Coping with boys (being boys)

Did you know: Males have more testosterone in adolescence than the rest of their lives put together.

Giddy in the evening?

The hormone increases through-out the day and peaks in the evening, making that the time of day when they are most excitable and distracted. It’s a good time to exercise their minds and/ or body. Humping often happens when they’re giddy and not sure what to do with themselves and can quickly become a habit devoid of sexual connotations. 

If they do begin twerking, try distracting them, asking for a game (maybe fetch/ tug/ find) so that their energy is put onto something more positive. A game with a toy will give them something to focus on and will lessen the chance of the humping becoming ingrained. If they are making advances towards you, then stand up, move away, then offer a game or toy.  It’s all about making the undesirable behaviour seem pointless and giving them an acceptable, alternate thing to do. If it hurts, let them know (like when they were a teething puppy) with a high, short noise (as much like a high dog in pain noise as you can manage). Be aware that sharp or long claws- especially the dew claws (the thumb- like ones) can quickly tear and ruin clothing.

Working on focussing and getting their attention will help, as will tasks like leave it, recall and emergency stops.

We’ve seen that the male implant works very well and seems to be kinder- and it’s much less permanent

If it’s still too much to handle, we are hearing some good things about the hormone therapy- male dogs can get an implant, similar to what is available for women. It’s a temporary solution- so it may need repeating 6 monthly or annually- which I think is reassuring, in case people change their minds or it doesn’t suit. When the dog matures, it may not be so necessary.

Neutering pros and cons: coping with seasons

I have 5 female dogs who are not neutered. Our girls “come in” together and we find it quite easy to cope with their seasons. A dog will have their first season at around six months (sooner for smaller breeds who develop faster, later for larger breeds) and usually a dog will have two seasons a year.

The first sign that a season is approaching is that some will mess up their bedding. They become a little more independent, some a little more wilful but not so much that it is a problem and nothing a long lead wouldn’t sort out. Roaming distance increases (the furthest distance which they feel comfortable roaming away from you). Their nether-regions swell and some dogs will spot blood. We advise to check thoroughly, as some girls will keep themselves very clean (a couple of girls have turned up for class whilst in season as their people did not realise… until the boys were very keen).

When the bleeding stops after just over a week, that is when they are most fertile. She will stand and “flag”, (or curl her tail to the side). They will be a bit more smelly (For a long  time I couldn’t tell, but I have smelt it now and it’s not pleasant- a bath helps); this scent lets the boys know that she is ready.

Close encounters 

Male dogs become extremely interested after finding a girl in season. Make sure she will not escape and consider if you need to walk in slightly more out-of-the-way places. You may need some ammunition- a favourite toy or some treats. If, while you are walking, a male dog does turn up, then it is not immediate panic stations.

Remember that they can’t get up to anything if the girl is sitting down. Maintain the sit, form the “Rear Guard” and ask the male dog’s owner to lead him away as your dog is in heat- most people will respond to a polite request. Most male dogs we have encountered are rather inexperienced and so it may be possible to use the confusion to call one dog away. If it goes wrong, don’t worry. Dogs “tie”, stuck rear to rear. For at least fifteen minutes. Use the time to contact your vet as there is a “morning after pill”.  We have never needed one, so far.

Neutering pros and cons: vet attitudes

Dog parents often tell me that they felt some considerable amount of pressure from vets to neuter their dogs.

the look of love

Although things have changed for the better in some Northampton vets, there are a couple of practices that haven’t changed with the times. We still hear that these vets spend more time talking about neutering pros (like the decreased risk of testicular cancer). People were horrified to learn that their vets did not explain. Vets left out important information and quoted the facts incorrectly.

Our customers say there was little chance to discuss health risks. Certain vets changed the subject when dog parents try to discuss the problems and alternates of neutering. This includes a 400% increase in risk of prostate cancer and the approximately 1 in 5 chance of female incontinence. Vets glossed over behavioural problems that neutering creates. They didn’t seem to recognise the proven facts: neutering will halt mental development, makes humping problems worse and increases the chance of aggression. People were horrified that vets were giving incorrect advice. Many suspected it was purposeful. They all said that they had lost trust and goodwill.

It’s better to prevent than try to cure. We can’t stand by and watch as people, who think they are doing the right thing, agree to neutering without realising the fuller picture. It’s time that everyone should only make up their own minds once they know all the facts.


“Long Term Risks and Benefits Associated with Spay/ Neuter in Dogs” L. J. Stanton MS 2007

 “Neutering in Dogs- Why?” by Mark Elliot BVSc VetMFHom MRCVS MLIHM PCH DSH RSHom

“Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers” Gretel Torres de la Riva, Benjamin L. Hart , Thomas B. Farver, Anita M. Oberbauer, Locksley L. McV. Messam, Neil Willits, Lynette A. Hart

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