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Cystic Ovarian Disease In Guinea Pigs

Guinea pigs are one of the commonest pets that we see in practice, and they make great pets!

Traditionally owners have been less likely to have the females spayed than some of our other common mammal pets, because entire females don’t have the obvious issues that we see with those other species. For example, female dogs will show obvious seasons twice a year, with associated behavioural changes and the inconvenience of dealing with it; female cats are at high risk of getting pregnant if they are not spayed; and entire female rabbits can be very hormonal and grumpy (and two female rabbits are likely to fight severely), as well as the risks of developing illnesses related to the reproductive tract as they get older.

Female guinea pigs will often live happily in an all-female group or with a neutered boar. This does mean, however, that we need to watch out for them developing cysts on their ovaries, as this is common and often goes unrecognised by owners, especially early in the condition.

Ovarian Cysts In Guinea Pigs

Ovarian cysts in guinea pigs are age related – around 80% of female guinea pigs over 18 months old will have some cysts present. Some of these are hormonally active, so cause obvious changes such as crusty nipples, behavioural changes (e.g. mounting other pigs), or fertility changes, but in 80-95% of cases they won’t be producing hormones, and these are the ones that traditionally have been considered to not cause clinical signs.

However, in my experience it often isn’t that they aren’t causing an issue, but rather that they are causing low grade or non-specific issues that can have an impact on the pig’s overall wellbeing, and often will contribute to other health problems.

Signs Of Ovarian Cysts In Guinea Pigs

Clinical signs from non-hormonal cysts (sometimes referred to as cystic rete ovarii) are most often associated with pain. These cysts will start small, but can get very large (up to 7cm is not uncommon) – it’s really common for these pigs to have a “weeble” shape with a very wide abdomen.

Owners often report that their female pigs don’t like being picked up, or vocalise when they lift them. We very commonly see urinary problems in these guinea pigs, as they aren’t able to comfortably get into the “correct” position for urinating, so they end up with sludge forming in the bladder, which is very irritant and can cause blood in the urine, infections, and urine stones forming – which of course creates even more pain.

Some guinea pigs will chew or overgroom the hair on their flanks because they are uncomfortable, or they may not eat as well as they should, or not be as active.


An experienced vet may be able to palpate cysts within your guinea pig’s abdomen, or an ultrasound scan might be advised. Although every vet is going to have their own opinion on whether a particular patient needs treatment, personally I generally advise surgery in the vast majority of cases where we have identified ovarian cysts.

Although they may not all be showing obvious clinical signs, guinea pigs are so good at hiding signs of pain that I prefer to avoid leaving them with conditions that are likely to be causing discomfort. It’s not unusual for us to remove cysts in older pigs (particularly ones rescued as adults with cysts already present) and their owner to then comment that the pig isn’t grumpy or lethargic after all!

Are There Risks To Surgical Removal Of Ovarian Cysts In My Guinea Pig?

Although traditionally surgeries on guinea pigs may have been considered more risky than in larger species, with modern anaesthetics and an experienced vet and nursing team, these surgeries are considered very routine and no more risky than other species.

Like with anything else, it’s important for guinea pig owners to get to know a vet who they trust and can build a relationship with, so that they can decide together what the best course of action is for a particular pig, and be happy that they are minimising the risks.

Some vets may have additional training or qualifications for treating exotic pets, while others may not have the formal qualifications but have a lot of experience. Most important is that they are experienced in dealing with guinea pigs, and particularly surgical problems, and that they are willing to work together with guinea pig owners to formulate the best plan for a particular situation.