Dog neutering – a guide to castration and spaying


  • ‘Neutering’ is an operation to remove the testicles or ovaries from a dog.
    • Castration = removing the testicles.
    • Speying = removing the ovaries (and usually womb).
  • Most dogs can be neutered from 6 months old.
  • Neutering is a routine procedure, performed by most vets on a daily basis.
  • There are very many benefits and few disadvantages to neutering.

General information

Neutering has many different names: castration, speying, ‘the snip’, ‘being done’, ‘being dressed’, all meaning the same thing, an operation to remove the testicles or ovaries. Castration is specific to male dogs (means removing testicles), and speying is the term for removing the ovaries (and usually the womb) from a female dog. Neutering prevents unwanted pregnancies, and provides a number of health benefits.

Reasons to have your dog neutered

Some of the benefits of neutering include:

Female dogs

Male dogs

  • Prevents testicular cancer
  • Reduces the chance of prostate problems later in life
  • Reduces the urge to find female dogs
  • Reduces the chance of unwanted behaviours related to hormones (such as humping or aggression)

When to have your dog neutered

Most dogs (both males and females), can be neutered from 4-6 months old. Early neutering has many benefits, especially for female dogs, however, it’s always important to discuss the decision with your vet because exact timings should be based on a number of different factors, including:

  • Breed/size: if your dog is a large breed, your vet might recommend neutering them slightly later. You can find out more in our neutering FAQs.
  • Behaviour: although some unwanted behaviours can be improved with neutering, some can actually be made worse (for example nervousness). For this reason, you should always talk to your vet or a qualified animal behaviourist before neutering your pet for behavioural reasons.
  • Weight: Your dog needs to be a healthy shape to be neutered because overweight dogs have a higher anaesthetic risk and more chance of complications during surgery.
  • Being in season/on heat: if your dog is in season, it’s best to wait for 3 months before neutering her. Neutering during a season can be risky and cause hormonal problems afterwards.
  • Other health conditions: if your dog is suffering from another health condition, especially one that is affected by hormones (such as juvenile vaginitis, pseudopregnancy, prostate problems or diabetes) it may change their ideal neutering time.

The procedure


  • Food and water - don’t feed your dog anything for 6-8 hours before their operation to make sure their stomach is empty (so they don’t regurgitate and choke under anaesthetic). This means no breakfast and no treats. Water is fine until 2-3 hours before their operation (i.e. take it up at 6-7am the morning of their surgery).
  • Health - let your vet know if your dog has any health problems, or if you’ve been concerned about them in the days leading up to their operation.
  • Cleanliness - if possible, make sure you dog is clean for their operation, bath them if necessary and remove any matted fur, mud or dirt. Don’t worry if you are struggling to do this, just speak to your vet beforehand.

Before the procedure

Your vet will check your dog over, settle them in a warm, comfortable kennel and give them a light sedative to relax and prepare them for their anaesthetic.

The operation

Your dog will be put under a full/general anaesthetic, their surgery site will be clipped and cleaned, and they will be given some pain relief. They will then be carefully monitored while they have their operation:

  • Females - an incision is made into the abdomen (tummy), so the ovaries and womb can be carefully tied off (with dissolvable stitches) and removed.
  • Males - a small incision is made at the base of the penis so each testicle can be tied off (using dissolvable stitches) and removed. If your dog is cryptorchid (one or both testicles haven’t dropped), their operation might be more complicated. However, it’s extremely important to have retained testicles removed because left alone, they can cause major problems.

You may or may not be able to see the stitches from the outside depending on the type your vet uses.

After the procedure

Your dog will wake from their anaesthetic under the careful watch of a vet and/or vet nurse. They will then be placed in a warm, comfortable kennel to recover. Most dogs can return home a few hours after their operation, but some need to be monitored for longer.

Recovery, home care and check-ups


When your dog first comes home, they might be a bit sleepy and disorientated. This can last for several hours, but they will start to feel much better as the anaesthetic drugs wear-off (usually within 24-48 hours). Once your dog is feeling brighter and more energetic, it’s likely that they will want to run around as normal, but it’s important that they rest for 7-10 days to prevent any complications with the wound and internal stitches. If necessary, you may need to keep your dog on a lead, crate them, or confine them to one room. Once they have recovered from being neutered, you will need to return them to exercise very gradually.

Protecting the wound

It’s likely that your dog will be given a protective cone/buster collar to stop them licking and nibbling at their wound. Speak to your vet beforehand if you would like a soft buster collar or a body suit for you dog.


Your dog will usually need a check-up 2-3 days and 7-10 days after their operation to check they are healing well and feeling better after their anaesthetic. Talk to your vet if you have any concerns about them before their check-up.

Stitch removal

If your dog has dissolvable stitches, they won’t need removing (dissolvable stitches are usually blue/purple coloured). If they have non-dissolvable stitches, they will need removing 7-14 days after the operation.


Neutering is a relatively safe, routine procedure, performed by most vets on a daily basis. However, like any operation, there are always risks and the potential for complications during and after the surgery.

Dog neutering cost

It’s impossible to say exactly how much neutering your dog will cost because prices vary between practices, and depend on the size of your dog and if they are male or female. If you phone your vets, they will be able to tell you their prices.

If you are struggling with the cost of neutering your dog, speak to your vet practice or your local dog warden about any charitable help that is available.

'Chemical' castration

For male dogs, there are injections and implants available that mimic the effects of castration. The benefit of these implants is that they don’t require a general anaesthetic and are reversible. Your vet might suggest chemical castration if they want to see the effects of it before performing a permanent neutering procedure.


Should my dog have a litter before I neuter her?

No, there is no evidence to show that having a litter benefits a dog.  Pregnancy/giving birth can come with complications and looking after a litter of puppies is hard work, expensive and time consuming - certainly not something to enter into without a great deal of thought and planning. If you want to breed from your dog, its best speak to your vet for advice to find out how you can do it responsibly and safely.

Will neutering make my dog fat?

No, neutering your dog won’t make them fat. However, after neutering your dog may not need as much food, especially as they are often neutered around the same age as they stop growing. Make sure your dog is fed on an appropriate amount of a complete diet that’s right for their life stage so they stay slim and healthy. In fact, you can buy special food for neutered dogs, which have the correct balance of nutrients and calories for them. If you’re concerned your dog is putting on weight after neutering, talk to your vet or vet nurse about the best ways to keep them an ideal body condition score.

I have a large or giant breed dog, should I wait to neuter them?

If your dog is a large or giant breed, your vet may advise you to wait until they are a bit older before neutering them. This is because they are likely to take longer to reach their adult size, and their growth plates (which control how long their bones grow) will take a few months longer to close. There is some evidence to show that neutering large dogs early (at 4-6 months), could lead to joint problems in later life. Talk to your vet to find out what age is best for your dog’s breed or size.

Will neutering my dog young make them dog incontinent?

USMI is a condition that causes a weak bladder and incontinence in female dogs. Some people think that USMI is more common in dogs that are neutered at a young age but there is currently no evidence that this is the case, and delaying neutering can increase the risk of some other conditions such as xxxmammary cancers. Speak to your vet if you’re worried about the best age to neuter your dog.

Can a dog be speyed while in heat?

Ideally not. Speying a dog in heat is much more risky because the blood vessels around the uterus become much bigger (and more likely to bleed), and hormonal problems (such as a long lasting false pregnancy) can develop afterwards. For these reasons, most vets recommend neutering 2-3 months after a season (unless there is a specific reason to do it sooner).

Why does my male dog still look like he still has testicles after his castration?

When a dog is castrated, the testicles (balls) are removed but the scrotum (ball sack) isn’t. This means sometimes they look like they still have testicles after their operation. Over time the scrotum will shrink and become less noticeable. If you notice swelling or redness in your dog’s scrotum after their surgery, contact your vet for advice. There are also two spherical glands called the ‘bulbus glandis’ that sit either side of the penis and swell when they become excited or aroused. These glands are often mistaken for testicles.

Does my dog need to wear a buster collar?

Yes, most dogs need to wear a buster collar or medical shirt to protect their wound after being neutered. If your dog licks or damages their wound they may cause complications such as infection or wound breakdown.

Will neutering stop my dog humping?

There are many reasons why dogs hump; sometimes because of hormones, but also because of excitement or habit. If your dog has suddenly started humping, speak to your vet to discuss whether neutering might help. If your dog’s humping is becoming a problem, the best thing to do is distract them every time they do it. Never tell your dog off - it’s natural so they simply won’t understand.

Does neutering help with aggression in dogs?

Aggression can be caused by many different things, including hormones, fear and trauma. Neutering can help with aggression, but also has the potential to make a dog feel more nervous and make the problem worse. If your dog is showing aggressive behaviour, discuss the options with your vet - getting help early is extremely important.

Is it too late to neuter my older dog?

Many people worry about neutering older pets, but in most cases it’s still a very safe and worthwhile operation, regardless of age. 

I’m worried my dog is pregnant, can she still be neutered?

Yes, in many cases it is possible to spey a pregnant dog. If you think your dog might be pregnant, contact your vet as soon as possible to discuss your options.

Can I neuter before my dog’s first season?

Yes, your dog can be neutered before their first season. In fact, neutering a female dog before her first season significantly reduces the risk of certain medical conditions such as mammary (breast) cancers and pyometra (womb infection).

What is a lap (or laparoscopic) spey?

Laparoscopic spey (or a ‘lap spey’) is a key-hole spey performed through three small holes and with the help of an endoscope (camera). Lap speys create much smaller wounds, tend to be less painful and invasive, and reduce the risk of certain complications. However, at present, they are only performed by specially trained vets and require special equipment, so aren’t available at all vet practices at this time.

I have unneutered female and male dogs in my household, what should I do to avoid unwanted pregnancies?

If you have an unneutered male and female in the same household, it’s a good idea to consider neutering one or both of them. If this isn’t possible, and your female dog comes on heat, it’s essential to keep your dog’s apart at all times to stop them from mating. Please remember that related dogs will mate, including brothers, sisters, fathers and daughters.

Will neutering give my dog cancer?

Neutering won’t give your dog cancer- in fact neutering will reduce the risk or completely prevent certain cancers for your dog. There are people who believe that neutering can increase the risk of certain cancers, but there is no solid evidence for this despite lots of scientific studies. And as neutered dogs tend to live longer than un-neutered dogs, it may be that any differences we see are actually related to the longer lifespan of neutered dogs instead of being related to the operation. If you have concerns about cancers or worried about the best age to neuter due to your dog’s breed or size, talk to your vet about the best time to neuter them.

Published: October 2020

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Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst