Neutering, spaying and castrating.

What do spay, castrate and neuter mean?

Neuter is the general term for the removal of all or part of the reproductive organs. It can apply to males (boars) or females (sows).

Spay is the term for removal of the female reproductive organs.A more technical term is Ovariohysterectomy (removal of ovaries and uterus). Spaying is a very invasive op.

Castration is the term used to describe a male neuter. The operation can be done many ways, incisions can be in various places, and a variety of stitching practises are used. This makes it extremely important that lots of research is done before choosing a surgeon.

A good vet will not expect to lose a guinea pig to a castration op unless he (guinea pig) has an underlying health problem that was undetectable at the pre op check. Obviously this is the risk with any operation.

The only reason to get a guinea pig castrated (male) is if he is going to live with a sow or for medical reasons i.e. tumours. Rescues often castrate their boars as it increases their chances of finding a new home. It is wrong to think that getting a boar castrated will change his behaviour significantly i.e. aggression, this does happen in other animals but not in guinea pigs. Any changes in behaviour that occur are likely to be due to the age of the guinea pig.

Sows no longer need spaying for cystic ovaries. There is a Chorulon Injection available or the cysts can be drained. Spaying is a very invasive surgery that most vets will not be keen to perform on a sow A few rescues also successfully spay their sows to prevent them from being bred from but the neutering operation is less invasive for the males.

As with all surgery there are risks. The only risk to a boar undergoing a castration op should be an undetectable underlying health issue (usually respiratory).

There are many ways of performing a castration; the one that you want is a successful one.

Firstly find a vet that a rescue uses successfully, at least you will know that they are seeing lots of guinea pigs- but check to see exactly how many and the time period they have been seeing them. The rescue may not like getting boars castrated so this op may not be done regularly.

There are different places incisions can be made with, it seems, varying degrees of success so do quiz vets on the amount of successful ops they have done, also ask them what they consider to be successful.
Expect guinea pigs to be ‘up and eating’ when you go to pick them up .


Guinea pigs do not need to be starved at all. A competent vet will simply flush the mouth out with water pre op to guard against guinea choking on any food that is left in the mouth. It is important to continue to feed them in case there is an emergency that comes into the vets and the op is put back until later, the shorter the time without food the quicker recovery will probably be.

Giving Rimadyl pre op will ensure that guinea is not in pain when he wakes and will start eating straight away. Metacam can be used but it has made some guinea pigs drowsy but it is better than no pain killer at all. Both are NSAIDs, and work in much the same way (anti inflammatory and pain killer).

The closed method of the operation should be (and is used by most vets) used as this carries less risk than the open method.

Vicryl should be used for stitching (not catgut) and glue for the outside wounds. Catgut should never be used in any operations on guinea pigs because it can cause inflammation; it is just a few pence cheaper than Vicryl so this cannot be used as an excuse.

Quiz the nurses on what they will do if a guinea pig is not eating the post op lunch that you’ve brought in (Grass is great to get them eating again). They should reply that they will syringe feed Oxbow Critical Care within an hour of him coming round and not eating. Critical Care Formula does not contain the fibre that is needed.

If you want your guinea pig to be given Rimadyl as opposed to Metacam then this can be written on the bottom of the permission form you sign.

Also write who should perform the op. This way if the chosen vet is called away to do an emergency, guinea won’t be operated on by someone else.

Preparation for a post castrate guinea pig.

Presuming that guinea is well and eating there are only a few changes that need to be made.

Bedding should be a veterinary bedding. This will minimise any wounds to the op site and keep it dry therefore at less from infection.

Hay should be in a tube or rack or just hanging but so that guinea cannot sit on it, to minimise injury to the site of the op.

There should be no drastic changes in temperature (but then there shouldn’t anyway, even with well pigs).

The site of the operation should not need cleaning, any pus or discharge means a prompt return to the vet. For skincare of post op guinea pigs contact info@gorgeousguineas.com, they can advise on which products to use on open skin etc.

Get used to what the site of the op feels and looks like. This makes it easier to monitor and recognise when/if things change.

If a post castrate abscess appears it will need lancing when ‘ripe’ and then daily flushing with sterilised water (such as Hartman’s Solution). As well as this Baytril at the correct dose must be given as there will be lots of toxins present. Along with Baytril a probiotic must be given. A Canula from your vet is very useful for flushing post castrate abscesses too.

The time for putting the boar with a sow(s) varies with advice from vet to vet. It should certainly not be before 2 weeks is up merely to allow for the wound to heal over satisfactorily. Bear in mind that healing can happen at different rates, always check your own guinea pig. The ‘medically’ safe time span to leave between introductions is 4 weeks. There are always exceptions to every rule though and some vets will advise as long as 6 weeks. Rescues often have no choice but to opt for the two week margin because of limited space available for seperate housing.

A boar will hassle a sow when first introduced, it is the animal way of saying ‘hello’, but she has defences and will soon use them if he becomes ‘too much’. Occasionaly a sow will full on attack a boar and the coupling of sows and boars should never be taken for granted.