Guinea pigs are growing in popularity as pets and we are starting to see more and more of them come through our clinics. They can make fantastic pets and are full of personality, however do require more care than many people think.  We get lots of questions about guinea pig reproduction and desexing so I thought I would cover some of our more frequently asked questions today.


How do I tell the gender of my guinea pig?

We use a number of techniques to do this depending on their age, some of which include:

  • Identifying if there are testicles present. Guinea pig males have well developed testicles that are generally easy to see on adults. In young guinea pigs they often haven’t yet descended making this technique more difficult.
  • Analyzing their reproductive anatomy. Males generally have a lower case “ i “ shape to their anatomy whereas females generally have a upper case “Y” appearance.
  • Palpating for ovaries in females – this technique should only be done by an experienced guinea pig vet

We often see cases where guinea pigs have been incorrectly identified as the wrong sex. A common scenario is when someone purchases two guinea pigs and are told they are two males or females. A month or so later they go to check the guinea pigs and find that all of a sudden there is a heap of babies running around! They then bring the guinea pigs in for us to check and we see that they actually had a male and a female that are now proud parents!

The above scenario is all too common and because of this we recommend that you bring any guinea pig that is recently purchased in for a health check and also to confirm their gender.


When can they start to reproduce?

Guinea pig males should be separated from any females, including their mothers and sisters, by around 4 weeks of age as in some cases they can be reproductively active from then. Most take a bit longer however it is best to be safe.


How many babies can they have?

Most guinea pigs have 2-4 pups (babies) however we have seen up to 12 at times, there are also reports of even larger litters.


How long do they take to develop and what do the babies look like?

The average gestation period (time developing inside the mother guinea pig) is around 63-72 days. This is much longer than many other small mammals like rabbits (who average 30-33 days). As their gestation period is much longer guinea pigs come out fully furred and looking like mini-adults (precocial young). They generally take 3-6 weeks to wean completely from their mother but can start eating some solid food from a few days of age.


Should I have my guinea pig de-sexed?

We recommend routine de-sexing (sterilisation) for all guinea pigs unless you are planning to breed them. The reasons are that it helps to prevent the following conditions from occurring:

  • Faecal impaction in males – this is where the male’s testicles and fat that is located around the testicles develop and start to stretch the skin. This can stop the guinea pig from being able to defecate normally in some cases and generally means that they need to have that area cleaned out at least once a day (often more regularly) by their owner.
  • Cystic ovarian disease in females – This is very common with some studies showing three out of four guinea pigs will develop this problem if left unsterilised. Cysts don’t generally always cause problems but when they do they can lead to hair loss, irritation and pain.
  • Reproductive cancers – these are seen commonly in both male and female guinea pigs


What is involved in the desexing surgery?

Every vet works a little bit differently but in most cases your guinea pig is dropped off in the morning to the vet clinic and then goes home late in the afternoon that day. During their visit they will have surgery under a full general anaesthetic to remove the main parts of their reproductive tract.


What are some common problems that occur with their pregnancy?

When guinea pig females (sows) reach 6-12 months of age their pelvis generally starts to ‘ossify’ which means that it can no longer separate to allow them to pass their babies if they become pregnant and haven’t been bred before. This doesn’t happen in all cases but when it does we generally need to perform a caesarian to remove the pups (guinea pig babies).

We also see a condition called pregnancy toxaemia in guinea pigs that are fed a sub-optimal diet so it is very important to make sure they are getting what they need.

If you have any further questions please don’t hesitate to get in touch. We have clinics in Perth and Melbourne but can also be reached by our website (www.unusualpetvets.com.au) and social media pages.