Dogs can be neutered from 10 weeks old- but is it wise?

Our wish is that people will have all the relevant academic and veterinary evidence so that they are fully informed and able to make up their own minds. 

otis weave

As with most controversial topics, opinion and fact can be easily muddled. We aim to concentrate on the facts. References are included so people can check up and they wish, do further reading. Where I offer my own thoughts, I have used this colour text.

Some may find it hard to believe that it is illegal to neuter in some Scandinavian countries, they say it creates more problems than it solves. Here it seems that vets and behaviourists cannot agree on whether it is sensible to neuter your dog at all, and if so, when would be the best time.

With any advice, my father would say “never let person who stands to gain [financially] help  make up your mind“.


Pressure to neuter increased from the USA, where cats are kept inside and dogs outside. This means that considerably more dogs were able to escape or roam free and inevitably, many ended up with puppies. Strays were a big problem and 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 and by 2007, there was significantly fewer strays and the number being killed annually had been reduced to 4 million (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 there were only 600,000 new puppies registered with the American Kennel Club in 2010.

In the UK, dogs are kept inside and cats are free to roam outside- the opposite to the US- so the stray population wasn’t such a problem. However, neutering was also promoted as as sensible and responsible here, and 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.

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. 

I’m alarmed that seemingly nothing has changed- neutering is still expected and encouraged. Our stray population is minimal so why are the supposed benefits still doing the rounds and why are facts being quietly ignored?

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. Another thing my Dad was fond of saying was “if it ain’t broke, don’t fix it”.

Let’s look at facts.

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 sensible to neuter cats, who go out and about independently. 

But what of the single dog from a “normal” loving  family? The kind of pet who would not be left to roam around on their own, who is with a conscientious family who wants the best for them? Is it sensible to neuter that animal?

2) Neutering to “control behaviour”.

Neutering halts mental development and it was traditionally thought that permanently juvenile dogs made more compliant pets. However, it is widely believed now 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 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 exasperate aggression. Neutered dogs are more likely to have noise phobias and be anxious or aggressive, the AKCCHF studies found. The rise in aggression scores corresponds with neutering under one year old in females, but occurred in dogs who were neutered at any age. (Please note that it is very rare that we see a “properly” aggressive dog, who would attack with little cause or warning).

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 consider other options. 

3) Neutering health problems- 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. As body proportions are altered, weight is distributed abnormally. This causes ligament and joint issues, most frequently in the legs and hips. Vet Mark Elliott (whose practice does not offer early neutering) has found that supplements for osteoporosis have helped those whose bone density was affected by neutering.

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!

I 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. If vasectomies and tube ties were done instead, then many of the health problems would be eased, as 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.

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 benefits and risks.

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

Health Benefits to neutering to male dogs

Health Risks of neutering to male dogs

* Castration reduces the less than 1% chance of testicular cancer to zero.

* The slim chance of non-cancerous prostate problems is also reduced.

* There is less chance of acquiring a perianal fistula (a rare but nasty problem, effecting mostly GSD in middle age)

* There is some (inconclusive atm) data that suggests there may a reduction in diabetes.

* If the procedure is done before the dog is one year old, there is a significant increased risk of osteocarcinoma (bone cancer) where it is prevalent amongst medium/ large breeds and the prognosis is very poor.

* The risk of cardiac hemangiosarcoma (a nasty rapid growing cancer of the heart) is increased by 1.6%

* Risk of hypothyroidism (under active thyroid) is increased by 300%

* Increased risk of progressive geriatric cognitive impairment

* Risk of obesity is increased by 300%

* The (0.6%) chance of acquiring prostate cancer by is increased by 400%

* The small (less than 1%) risk of urinary tract cancers is increased by 200%

* Risk of orthopaedic disorders is significantly increased, including doubling the chance of hip dysplasia. The chance of a cranial cruciate ligament tear increases from 0.0? to 5% in early-neutered males

* Increased risk of adverse reactions to vaccinations

 * Almost 10 percent of early-neutered males were diagnosed with lymphosarcoma (cancer in the blood). It’s 3 times more likely in early neutered males.

Health Benefits of neutering to female dogs

Health Risks of neutering to female dogs

* The situation is more complex, as risks of various health problems are different between different breeds.

* Overall, neutering reduces the (1%) risk of pyrometa (serious uterine infection).

* It diminishes the (less than) 0.5% risk of uterine, ovarian or cervical cancer.

* There is less chance of acquiring a perianal fistula (a rare but nasty problem, effecting mostly GSD in middle age).

* If done before 2.5 years old, the risk of mammary tumours is reduced.

* “spay incontinence” (inability to control the bladder due to the operation) is caused in 4 – 20% of female dogs.

* There is a significantly increased risk of a recessed vulva, of vaginal dermititis and vaginitis, especially if the procedure is done before puberty.

* If the procedure is done before the dog is one year old, there is a significant increased risk of osteocarcinoma (bone cancer) where it is prevalent amongst medium/ large breeds and the prognosis is very poor.

* Spaying increases risk of splenic hemangiosarcoma (a nasty rapid growing cancer of the spleen) by 220% and the risk of cardiac hemangiosarcoma (a cancer of the heart) is increased by (just under) 500%, causing the deaths of 8% percent of girls neutered after their first birthday 

* the risk of mast cell tumour increases from 0.0? to 6% in females neutered after 12 months

* The risk of an under-active thyroid is tripled.

* Risk of obesity is increased by 300%

* the risk of persistent urinary tract infections is increased by around 350%.

* doubles the small risk (less than 1%) of urinary tract tumours

* Risk of orthopaedic disorders is significantly increased, doubling the chance of hip dysplasia 

The chance of a cranial cruciate ligament tear increases from 0.0? to 8% in early-neutered females

* Increased risk of adverse reactions to vaccinations


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.

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 owners 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 owners 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.

Male dogs will be very interested, so 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 owners 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 will “tie” and be stuck rear to rear for fifteen minutes or more, use the time to contact your vet as there is a “morning after pill”.  So far, we have never needed one.


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

the look of love

They were told of the benefits, (like the decreased risk of testicular cancer) but were not told (or were given incorrect facts) when it came to discussing the problems neutering can cause. Owners say there wasn’t the same chance to discuss either the health risks of neutering (including a 400% increase in risk of prostate cancer and the approximately 1 in 5 chance of female incontinence) or the behavioural problems that neutering creates (including the proven facts that neutering will halt mental development, make humping problems worse and there is more chance of aggression).

In truth, we do stand to gain financially as we are frequently hired to solve the resulting problems that neutering creates, but we feel it is better to prevent than try to cure. We feel we can longer stand by and watch owners, who think they are doing the right thing, agree to neutering without realising the fuller picture. It’s time that responsible owners are given all of the facts so they can make up their own minds.


“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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