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Neutering: fact and fiction

The question of whether or not to have a pet dog neutered is faced by most owners at some time. It is hoped that the following information will be of assistance to you in making an objective and informed decision.

Neutering is a surgical procedure, carried out under a general anaesthetic, to remove the internal reproductive organs. In a bitch this is called spaying and involves the removal of the ovaries and uterus (ovariohysterectomy). In a dog this is called castration and involves the removal of both testicles (orchidectomy/orchiectomy).

The benefits of spaying

Bitches usually come into season (also known as heat or oestrus) from about the age of six months. Thereafter the seasons continue at approximately six-monthly intervals for the life of the bitch. The duration of each season is 3-4 weeks. To prevent accidental pregnancy the bitch must not be allowed contact with any intact dog during this period. This will mean confining her during times that you are unable to provide constant vigilance over her and limiting her exercise to a great degree as she will be extremely attractive to any entire dog that scents her. She will lose blood during this period and the inevitable spotting on carpets and furniture may be a problem.

Around this time ( prior to, during, and after, her season) the bitch may exhibit undesirable changes in temperament and behaviour due to hormonal changes. She may become moody, aloof or clingy, restless, irritable, eating habits may change, etc. Many females will actively attempt to seek out a mate by escaping over, under, or through fences. Spaying will effectively extinguish this urge and thus prevent not only an unplanned/unwanted litter but also avoid the risks associated with wandering, for example: getting lost, impounded, stolen, road traffic accidents, injury from fighting or mating, infection and disease contracted through contact with sick dogs, eating dangerous substances, etc.. A further advantage is that, as she will not be sexually attractive to males, there will be no howling, fighting, leg-lifting visitors courting her.

A common condition which occurs in intact bitches and which is eliminated by spaying is false pregnancy (phantom pregnancy, pseudopregnancy, pseudocyesis). About 4-6 weeks after her season an affected bitch will show many, or all, of the signs of pregnancy. She may seem anxious, produce milk, make a nest, attempt to nurse objects such as toys, in short she will display typical canine maternal behaviour. This condition affects around 60% of intact bitches and is caused by the hormonal changes associated with oestrus. Once it occurs, the bitch is likely to continue to experience false pregnancies of increasing severity after each season. (Evans & White. p.153)

Castration eliminates or reduces the risks of developing certain health problems.

Mammary cancer is the most frequently occurring cancer detected in unspayed bitches. 26% of intact bitches develop tumours of the mammary glands and of these, 45% are malignant and 55% are benign (Giffin & Carlson, p.488 ). The risk of these tumours developing is significantly reduced if the bitch is spayed at a young age. Spaying prior to the first season reduces the risk to 1%. Spaying between the first and second seasons reduces the risk to 8% (Giffin & Carlson. p.489). The older the bitch at the time of spaying the less protection will be afforded by the operation.

There are also other health benefits which should be taken into consideration. The chance of developing pyometra, which is a very serious, life-threatening infection of the uterus is completely eliminated, as are other problems associated with the reproductive tract such as uterine and ovarian cancers, cystic ovaries, uterine torsion, vaginal hyperplasia, etc., together with the possible complications of pregnancy and whelping.

Disadvantages of spaying

Some spayed bitches may develop urinary incontinence. This means that, when relaxed or asleep, a small amount of urine will dribble out. It can occur at any age but would seem to be more common in the older bitch. It can be quite distressing for a housetrained dog, but the problem is easily controlled by medication.

In some breeds it is possible, but not inevitable, that spaying will cause a change in the growth and texture of the coat. This may look unattractive and make grooming more difficult. This side-effect is not generally associated with short-haired, smooth-coated breeds.

If a bitch displays dominant aggressive behaviour then she should not be spayed as this will exacerbate the problem due to the lowering of oestrogen levels. (Munns, 1998 )

The benefits of castration

Castration eliminates or reduces the risks of developing certain health problems. Obviously, the removal of the testicles eliminates the possibility of testicular cancer and other tumours of the testicles as well as testicular torsion. The chance of prostate enlargement caused by benign prostatic hyperplasia, prostatitis, and prostatic cancer is minimized (Giffin & Carlson.. p.375-376) Perianal adenomas, which may become malignant adenocarcinomas occur primarily in intact males (Giffin & Carlson, p.266). Feminization is associated with intact males suffering from Sertoli cell tumour of the testicles.

Once a sexually mature dog becomes aware of the presence of an in-season bitch the drive to mate takes over. If the dog is confined he may howl, become restless, depressed, lose interest in his human family, ignore commands, lose appetite, and scent mark inappropriately. He will try by all means to escape and what may appear to be a very secure garden is frequently no match for a determined Romeo. Once out and roaming the dog faces all the dangers, injuries, and diseases described above.

Castration is not a curative for all forms of aggression but it may have the effect of lessening intermale aggression and other dominance-based aggressive behaviours. Caution should be exercised in the case of aggression between two males in the same household. If there are dominance problems between them then, in this case, the less dominant dog should be castrated. Castration may also result in a less territorial dog and one that is generally calmer and more tractable.

Importantly, the castrated dog is unable to sire a litter of unwanted puppies.

Disadvantages of castration

Some owners may find the appearance of a dog minus testicles disconcerting or unappealing. Testicular implants are now available and whether these are an appropriate option should be discussed with your veterinarian.

If a dog is displaying fear-based aggression then castration is contra-indicated as the lowering of testosterone levels consequent upon the operation may aggravate the problem.

When to neuter


This should be discussed with your veterinarian as some may advise spaying before the first season, others prefer to perform the operation three months after the start of the first season.


Castration is usually carried out at around the time of puberty which may vary slightly from breed to breed. The optimum timing for the operation should be discussed with your veterinarian and, if possible, a breed expert.

Myths of neutering

Neutered dogs become obese and lazy.
It is a very common misconception that castration or spaying will cause the dog to become fat and lazy. The truth is that it is over-feeding and insufficient exercise which gives rise to the problem of weight gain and consequent lethargy. The age at which dogs are usually neutered frequently coincides with the slowing down of the rapid growth of puppyhood. Continuing to feed the high calorie diet needed for growth may contribute to overweight. An age-appropriate diet and suitable exercise will ensure that the dog remains trim and energetic.

A bitch needs to have at least one litter.
There is no physiological or psychological benefit to a bitch in having a litter. Indeed, pregnancy and whelping can be very stressful and the potential complications may be injurious or even fatal for the bitch.

Mating is natural and therefore necessary.
How ‘natural’ is the life of a domestic dog? We house, feed, vaccinate, worm, medicate, train, protect, pet, play with, and generally do all we can do keep our dogs happy and healthy. Praiseworthy? Yes. ‘Natural’? No. The imperative to breed is entirely hormone based and once the hormones that drive the urge are removed so is the urge. What is not experienced is not missed. Dogs do not dream of motherhood or fatherhood and raising offspring.

Male dogs will be better behaved if allowed to mate.
Mating will not solve behaviour problems. On the contrary it may cause such problems to become worse. Having mated once the dog will show an increased interest in bitches and he may also consider his status elevated, both of which may make him less controllable and less likely to obey commands.

Neutering will change the character.
None of the positive characteristics of the dog will be altered. The dog will be just as loving, protective, playful, etc. Physical development and mental maturity are rarely affected.

Evans J. M. & White, K. Book of the bitch. Dorking, Surrey: Interpet Press, 1995
Giffin, J. M. & Carlson, L. D. Dog owner’s home veterinary handbook. 3rd ed. N.Y.: Howell Book House, 2000
Munns, M. ‘Dominance aggression’. Golden Retriever News. March-April 1998
Smith, I. L. Spaying and castration: pros, cons, myths, and Dobermans. 2000
Turner, Trevor, ed. Veterinary notes for dog owners. London: Popular Dogs, 1990

Your comments and views:
Joined: May 2004
Posts: 49,483
Female  Diamond Supporter 
06-06-2005, 07:57 AM
Whether or not one should have their pet dog neutered is a question that frequently arises on Dogweb and in order to make this decision it is important to know all the facts. This article by Dogwebber Shadowboxer covers all the main details both for and against and will be a great help to anyone looking for information on the subject. Thank you Shadowboxer,a very interesting and informative article.
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Dogsey Senior
Joined: May 2005
Posts: 503
08-06-2005, 10:26 AM
Thank You Shadow Boxer. I had already decided to have Millie Spayed. She is waiting until July before she has the op. She finished her first season just 2 weeks ago. Your very informative article has helped in my resolve. It was very fair and anyone with any worries about the subject will find it very helpful.
Many Thanks,

Anne W.
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Dogsey Veteran
Joined: May 2004
Posts: 12,204
11-06-2005, 09:07 AM
Fab article! Very useful and informative.
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Dogsey Senior
Joined: Mar 2005
Posts: 445
11-06-2005, 12:45 PM
Great article; all the facts in one place - rather than having to hunt around for them - thank you!

Can I add that in some breeds the coat is effected by neutering/speying, but that it has successfully been overcome in some dogs by supplementing the diet with fish oils?
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Almost a Veteran
Joined: Sep 2009
Posts: 1,114
26-01-2010, 12:45 PM
Excellent article - especially the section "Myths of Neutering - Mating is Natural and therefore necessary" Everyone should read this article when considering the welfare of their dog
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Dogsey Veteran
Joined: Sep 2010
Posts: 1,676
14-01-2011, 05:43 PM
Has helped to make a difficult decision, many thanks
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New Member!
Joined: May 2012
Posts: 11
18-07-2012, 03:00 PM
Brilliant article thank you:)
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Dogsey Veteran
Joined: Nov 2010
Posts: 14,404
18-07-2012, 05:12 PM
Science has moved on quite considerably since this original article was written and there are great deal more pros and cons to neutering both males and females than identified in this particular point of view.
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New Member!
Joined: May 2012
Posts: 11
18-07-2012, 08:13 PM
I've been reading a lot of the new threads on neutering as I know the husky we are rehomming isn't and Im not sure if he should be. However everything points to a lengthy discussion with our vet and maturity ages. My reason for neutering would be that I don't ever want to breed him as there are far too many puppies out there. But I guess as he's a he and not a she it's not soo much of a problem:)
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