Neutering or spaying your cat: what you need to know

The operation is done under general anaesthetic and afterwards your cat cannot have kittens. In a tom both testicles are removed: castration. In a queen the ovaries are removed, sometimes together with the womb: spaying.

Words differ between countries. Strictly, sterilising only cuts the tubes and leaves the sex organs in place, while castrating removes them. In practice vets usually remove the organs in cats of both sexes, so everyday words for 'sterilising' often mean a full neutering. This page says 'neutering' for both.

Because the sex organs are removed, the cat also loses its sex drive and the hormone swings that go with it. That is why neutering changes behaviour such as spraying and roaming, which plain tube-cutting would not.

It is one of the most common operations in veterinary medicine and is generally considered very safe, but every operation under anaesthetic carries some risk.

Surgery is still the established way to neuter a cat. Non-surgical methods and hormone-sparing operations exist only as research, mostly in dogs, so they are not options to count on for a cat.

The main reason is no unwanted kittens. A queen can get pregnant from about 4 months old, and neutering is the only fully reliable way to prevent that. Keeping an unneutered male and female together is no safeguard, even when they are brother and sister. One queen can have about 3 litters of 3 to 6 kittens a year. Kittens without a home end up in shelters or on the street, which is why welfare groups ask owners to neuter and chip their cats.

A queen who is not spayed comes into heat (krols) again and again. She calls loudly, is restless, and tries hard to get outside to find a mate. After spaying she no longer comes into heat. Toms who are not castrated roam, fight and spray strong-smelling urine to mark their territory. Castration lowers all three, and a cat neutered before the habit starts may never begin to spray. Even indoor-only cats spray, so neutering is advised for indoor cats too.

Fewer fights means fewer bite wounds and abscesses, and less spread of the viruses FIV (cat aids) and FeLV (cat leukaemia), which pass mainly through bites and are more common in unneutered males. A neutered cat also roams less and stays closer to home, which lowers the risk of road accidents and of getting lost.

Without a womb, a spayed queen can no longer get a womb infection (pyometra, a pus-filled womb that can be fatal). Ovarian and womb cancer and difficult births also disappear. A rare stump pyometra can still occur in a spayed female. In a tom, the risk of testicular cancer goes and an enlarged prostate is less likely. A cat with a testicle that stayed inside the body should be neutered, because the retained testicle is more likely to turn cancerous or twist.

Mammary tumours are the third most common cancer in cats, and more than 90% are malignant. Spaying before the first heat is linked to a much lower risk. One 2005 study found an 86% lower risk when females were spayed before 1 year old. The evidence is weaker than it sounds: a 2025 review of four studies rates it weak, though the protection seems larger the earlier the cat is spayed. Spaying after about 1 year has not been shown to lower the risk.

In some large pet-record datasets neutered cats lived longer (about 62% longer for males and 39% longer for females in one). That does not prove the operation adds years: neutered cats may simply roam and fight less and be better cared for.

Neutering also lowers the cost and worry of things that go with an entire cat: fight wounds, abscesses and, in females, treating pyometra or tumours. One US charity says treating pyometra or reproductive cancer can cost five to ten times a routine neutering.

Neutering mainly removes behaviour driven by sex hormones: calling in heat, spraying, roaming and fighting. It does not change a cat's basic personality. Several sources say neutered cats become calmer and more affectionate towards people. A vet information centre cites a study of about 1,660 cats in which neutered cats became more affectionate.

Spraying, roaming or mounting can carry on for several weeks after the operation, because hormones fade slowly, and a learned habit can stay. A cat that sprays long before the operation is less likely to stop. If a neutered cat suddenly starts to spray, talk to your vet: stress or an illness may be behind it.

Older studies also report some downsides. One 2007 study of 859 cats found more shyness in early-neutered cats, but less asthma, gum inflammation and hyperactivity. A randomised study of 800 cats found no effect of the age at surgery on unwanted behaviour up to 24 months. The evidence is mixed and mostly small.

Vet guidance for house cats is that neutering at about 4 to 6 months is safe, and many guidelines advise waiting until after the kitten vaccinations. The vet takes the cat's physical and behavioural development into account. Since 2016 an international task force of 11 vets (the Feline Fix by Five Months campaign) advises neutering cats by 5 months old, before the first heat, backed by US vet bodies. Cat charities in the UK say 4 months, and some say '4 months or earlier'. Your vet may advise differently.

Queens can get pregnant from about 4 months old, possibly 3. Males are on average sexually mature at 8 to 9 months, but some already at 4 months. A litter can come before your cat looks grown up.

In practice, vets differ. In a 2021 US survey 61% of vets said 5 months or younger is best for females, but 57% waited until males were 6 months or older. Older advice was often 6 to 9 months. No study clearly shows one best age. The choice depends on the aim and the situation, and the vet weighs it for each cat together with you.

Early neutering (a kitten from about 9 weeks) is accepted in veterinary guidance for stray and shelter cats to limit the surplus of cats. Neutering under 8 weeks is rejected, because kittens that young do not eat enough solid food to recover. Guidance for shelter and stray projects uses at least 8 weeks and 1 kg.

A practical tip: wait until the kitten weighs more than 1 kg and is vaccinated. Neutering during the vaccination series does not make the vaccines work less well, according to a US study cited by a vet information centre.

Very young kittens need extra care: they can get cold or have low blood sugar under anaesthetic, so they are kept warm and fast only briefly. Not every practice has the monitoring equipment for kittens. The same sources find that surgery is quicker and recovery faster in young kittens.

Concerns about early neutering include urinary blockages and bone or joint problems. Vet reviews and the Fix by Five advisors say these are not supported by research. Early neutering may delay closing of the growth plates, which does not change adult size; veterinary guidance mentions a possibly higher risk of a growth-plate problem in some breeds such as the Maine Coon, with limited evidence.

An older cat can still be neutered. In most cases it is still a very safe and worthwhile operation at any age. If you think your cat may be pregnant, call your vet as soon as possible: in most cases a pregnant cat can still be spayed. A cat in heat can be spayed too, though it is slightly more risky.

Your cat should be healthy on the day. Tell the vet about sneezing, eye discharge, vomiting or diarrhoea in the days before: the operation may be postponed.

The practice tells you when to take away food (water is usually allowed until the morning). The stomach must be empty so the cat does not vomit or choke under anaesthetic. Times differ between practices, and young kittens usually fast for a much shorter time than adults, so follow your practice's instructions exactly.

Many vets run a blood test before anaesthetic in older cats and place a drip. If your cat is not chipped yet, ask for the chip to be placed during the same anaesthetic.

Male: both testicles are removed through a small cut over each one in the scrotum. The wound is usually not stitched. Female: the ovaries (sometimes the womb) are removed through a cut in the flank or in the belly. Stitches may be under the skin and dissolve, or have to be removed after 7 to 14 days.

Most cats go home the same day, a few hours after the operation, and are up and about within an hour or so of waking. Some vets keep a cat overnight for observation. Anaesthetic takes about 12 to 48 hours to wear off fully. Nausea and drowsiness the first day are usual and temporary. The vet may give pain relief for a few days.

Give your cat one quiet, warm room with a low bed, water and a low-sided litter box. A small meal a few hours after coming home is usual. A recovery cone, a soft collar or a body suit protects the wound: licking can cause swelling, reopening or infection. Many practices do not include the cone or suit in the price, so ask.

Keep activity low: no running, jumping or rough play. Females need about 10 to 14 days of rest; males need much less and are usually healed in 7 to 14 days. The vet tells you what applies to your cat.

Keep the cat indoors until the vet says it may go out: a female for roughly 10 to 14 days, a male until the wound has healed. A neutered male can still be fertile for up to 49 days after castration, according to a vet information centre, so keep him away from unneutered females in that time.

Look at the wound every day. Do not bathe the cat or put ointment on the wound or clean it unless the vet says so. Paper litter for about a week keeps granules from sticking to the cut.

Females usually have a check 2 to 3 days after the operation and again 7 to 10 days after it; males often need one check or none. After castration the empty scrotum stays for a while and slowly shrinks. Swelling or redness there is a reason to call the vet.

A cat with an undescended testicle needs a bigger operation and may recover more slowly. Hair that grows back over the wound can be darker for a while, especially in Siamese cats; it grows out with the next moult.

Neutering is the best-known risk factor for obesity in cats, whatever the age at which it is done, and the risk is higher in males. Cats fed freely can put on weight and fat within 8 to 12 weeks of the operation. The main reason is that neutered cats eat more: falling sex hormones, especially oestrogen, seem to raise appetite, while the energy a cat needs falls at the same time. Gain can start within a couple of weeks. In one study of nine male cats fed freely, body weight rose about 20% in six months, mostly fat.

It is not unavoidable. Cats do not turn fat and lazy because of the operation: weight gain is controlled with the right amount of food, set meals and play. Neutered cats need noticeably fewer calories. The amount to feed is for your vet or vet nurse to work out for your cat.

Vets advise set portions instead of a bowl that is always full. In a study, a lower-fat, lower-energy food fed in controlled meals reduced weight gain after neutering. Food made for neutered cats exists; ask your vet whether it suits your cat, and do not switch a growing kitten to an adult diet too early.

Weigh your cat and check its body condition regularly, for example every two weeks while it is still growing. The visit for the operation is a good moment to ask the vet for the current weight and how to score the body condition at home. Overweight cats are more likely to get diabetes, joint pain (arthritis), liver problems and, in males, urinary blockage. Even when weight is lost, regain is common, so preventing the gain is easier than losing it.

Sources disagree on whether early neutering raises the weight risk. Some vet guidance mentions a higher risk after early neutering; other guidance and a US review find no link between the age at neutering and final weight. The small studies on this are partly funded by pet-food companies.

Neutering is routine and complications are uncommon. A US review reports problems in about 2.6% of 1,459 cats, mostly minor, such as inflammation at the wound. Possible problems: swelling, wound infection or the wound opening (often from licking), bleeding and, rarely, a reaction to the anaesthetic. Infection is rare and is usually treated with antibiotics.

A cat that was not fasted can vomit under anaesthetic and breathe the vomit in, which is why the fasting instructions matter. In one study the risk of dying from anaesthesia was about 0.11% for healthy cats and about 1.40% for sick cats. The study covered many procedures, not only neutering.

Urinary problems in neutered cats are debated. Several reviews found no link between neutering and a narrow urethra or blockage. One large records study found neutered cats of both sexes had a higher risk of lower urinary tract disease, and overweight cats are at more risk. The vet can talk through your cat's urine habits.

Neutered cats had a higher chance of diabetes in one study (8.7 times the odds), though diabetes is rare in cats and breed, age and weight matter too.

Prices differ a lot between practices and countries, and a female usually costs more than a male because the operation is bigger. Ask for a quote beforehand and ask what is included: the cone or suit, the check afterwards, pain relief and the stitches. A blood test before anaesthetic costs extra (often advised for cats over about 7 years). See your country's block for typical ranges.

Cat insurance often does not pay for neutering, because it counts as preventive care. Some insurers sell an add-on for preventive care that does. Check your policy. Some local authorities give residents a discount voucher or subsidy for neutering, sometimes a lower rate for lower incomes. Look on your local authority's website before the operation.

Any vet practice can neuter a cat. Compare quotes and ask about their kitten anaesthetic, stitches and aftercare. For a very young kitten, ask whether the practice monitors kittens (pulse, breathing, ECG) and has gas anaesthesia.

Cats adopted from a shelter are usually already neutered, so ask before you adopt. Stray or semi-wild cats can be neutered through local stray-cat projects. The vet usually marks the cat with a notch in an ear so everyone can see it has been done.