Our advice on neutering your pet

There are many pros and cons of having your pet neutered. This information sheet is to help you make an informed decision regarding neutering and whether it is right for your pet. If you have any more questions you can discuss them with a vet or Carol, our pet health/behaviour counsellor.

Male dogs

Having a male dog neutered (castrated) involves a general anaesthetic and the removal of both testicles. Advantages can be a decrease in sexual behaviour (mounting & territorial urine marking), less inclination to roam and the more obvious advantage of preventing unwanted puppies if he lives with an un-neutered bitch.

Castration also reduces the risk of various health problems in later life including diseases of the prostate and testicles, anal disease and some hernias. Castration is unlikely to have any beneficial effect on problems related to being left alone, house-training problems, or general boisterousness.

Castration may not be advisable in very nervous dogs nor in some cases of aggression. In these cases please discuss with Carol first. Castrated male dogs have a tendency to put on weight and it is important to monitor this and cut down on food intake if necessary. In addition some dogs experience a change in coat condition or slight changes in character.

We recommend waiting until your dog is a year old before having him castrated, although in certain circumstances it can be done earlier.

Female dogs

The argument for having a female dog neutered (spayed) at an early age is strong. Spaying involves a general anaesthetic and removal of both ovaries and the womb (uterus). If it is carried out before the second season there is a greatly reduced risk of mammary (breast) cancer developing later in life.

It also prevents the development of womb infections that are common in unspayed bitches and can be fatal, often requiring emergency surgery. Other advantages are the prevention of ovarian and uterine cancers and false pregnancies, and better control of diabetes mellitus.

Like castrated dogs, spayed bitches are also prone to weight gain, but this is prevented if care is taken with feeding. Coat changes can occur, and there may be a slightly increased risk of urinary incontinence in spayed bitches (although this usually responds to medical treatment).

We recommend spaying 17 weeks after the first day of a season, normally the first season. The timing of this is important due to hormonal factors. In some circumstances we will spay a bitch before her first season – please discuss this with a vet first.

All anaesthetics and surgical procedures carry some risks. If you have any further questions please feel free to ask a member of staff.

The current age recommended for neutering both male and female cats is 4-5 months old providing that they are over 2kg in body weight. There are many advantages of neutering in cats:


Having a male cat neutered (castrated) involves having both testicles removed under general anaesthetic. Advantages can be a decrease in sexual behaviour, territorial urine marking, less inclination to roam and therefore much less likelihood of being involved in road traffic accidents.

Letting younger male cats outside prior to neutering puts them at much higher risk of being attacked by larger male cats in the neighbourhood, due to their small size and entire status.

Un-neutered males have more of an inclination to be involved in cat fights, the injuries from which have a range of severities and most respond well to symptomatic medical treatment. The problem of most concern is that the cat may contract FIV (feline immunodeficiency virus – the feline equivalent of AIDS) and FeLV (feline leukaemia virus) from other male un-neutered cats. Both of these conditions affect the immune system and have several consequences.

They can lead to an early death. FeLV can be vaccinated against in the recommended kitten vaccinations for outdoor cats; there is no vaccination currently against FIV. If an older stray cat is coming in for neutering and vaccinations, we recommend a simple blood test which takes about 30 minutes to run to see if the cat has contracted FIV/FeLV so that the appropriate precautions can be undertaken for the rest of the cat’s life.


There is a strong argument for having a female cat neutered (speyed). Speying involves removal of both ovaries and the womb (uterus) under general anaesthetic. The most common reason for speying is to prevent unwanted litters. Cats are induced ovulators, which means that as soon as un-neutered females is mated, an egg is released and she has a very high chance of becoming pregnant.

Recent studies have shown that 8 out of 10 litters are unplanned and many of these are from female cats under 6 months of age. This unfortunately results in approximately 250,000 unwanted cats each year entering rescue centres.

Disadvantages of neutering in both sexes:

Research has not given definitive answers but there is some suggestion that neutering may contribute to obesity and some suggestion that cats may be ‘shyer’ following neutering at a young age.

All anaesthetics and surgical procedures carry some risks. If you have any further questions please feel free to ask a member of staff.

Post Operative Feeding Regime for Neutered Dogs

Most dog owners are not aware of the changing dietary requirements of an animal after it has been neutered. After an operation to remove the ovaries and womb (in a female dog) or the testicles (in a male dog) the metabolic rate, and therefore dietary requirement is lowered.

This means neutered dogs will require less food to maintain their body weight than before their operation. This includes when neutering is performed for a medical reason e.g. womb infection or testicular tumour

This has been shown by many studies, and also our own experience. Animals tend to gain a fair amount of weight after neutering if their diet remains unchanged. The weight gain is often more marked in animals neutered under a year old, i.e. in females neutered before a season, but is seen in the majority of neutered dogs. If an animal is overweight and already on a reduced feeding regime before their operation then weight loss is slower after the surgery than it was before.

After a dog is neutered we recommend reducing their diet to 2/3 of their previous feeding amount. Alternatively a change to a food for ‘neutered animals’ or if an animal was overweight at the time of the surgery, a change to a low fat diet or a ‘light’ version of their current commercial diet is a good first step.

Weighing out a dog’s food every day is a good way to make sure they receive the appropriate amount. Animals should always be fed for their ideal weight and not their current weight. Treats or additional food stuffs e.g. table scraps, if fed, would need to be taken into account and therefore a reduction made in the dog’s daily wet/dry food intake.

Please bring your dog into the Cassiobury Surgery, or arrange a weight appointment at Katherine place for your pet 2 weeks after their operation and again 4 weeks after their operation. Monthly weight checks after this would be advised for the next few months. This will keep check of your pet’s weight and allow early intervention if they are showing weight gain to help prevent obesity.

We provide free of charge weight clinic appointments with our nurses for any dog that is overweight to help you know what to feed and how much your dog needs. Prior to the appointment an accurate food diary (including weights of food) of everything the dog eats for a week needs to be submitted for us to analyse before the appointment.

We will work together with you and your dog to make dietary alterations to achieve the appropriate weight loss. An appointment would need to be booked with reception either in person, or by phoning 01923 223321.

Neutering Ferrets

The current protocol has shown that neutering in both male and female ferrets is NOT advisable due to the procedure being proven as a cause of Adrenal Gland Disease (AGD) which is very unpleasant and nearly always results in the euthanasia of the affected ferret at some stage in their life. The younger the animal is neutered the quicker the onset and more severe the signs of AGD.

The most common clinical sign of AGD is progressive hair loss from the tail to the head. Some ferrets are very itchy and they can also have skin thinning. In the later stages weight loss develops, there is a distended appearance to their tummy and they become very weak. This is a condition seen very rarely in entire ferrets or those who have been implanted but in nearly 100% of ferrets that have been neutered.

The current recommendation for male ferrets is the implantation of 9.4mg Suprelorin implant as it holds a veterinary license for the chemical neutering of male ferrets. The 4.7mg implants have been used successfully for the chemical neutering of both sexes for many years. The smaller implant will need replacing after 1-2 years but the larger one (only for use in males) may last up to 4 years.

The Suprelorin implants have been shown to not only be effective in preventing the sexual unpleasantness of ferrets (including the smell) but also to prevent adrenal gland disease.

If ferrets are placid and like the taste of ferretone they may be able to be implanted conscious, if not a short sedation may be required for implantation.

An alternative to implantation for females is a Delvosterone injection after the onset of a season. This may need to be repeated and some require up to 3 injections per year.

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