A sebaceous cyst, also known as an epidermoid cyst, is a lump or node on the skin filled with a thick, paste-like, greyish-white substance. It is the most common tumour found in guinea pigs but is benign (non-cancerous).
These cysts result from hair follicles that have become clogged, trapping a mixture of sebum and dead skin cells. The dense, soft content inside the cyst can be felt when touched or gently pressed.
Sebaceous cysts are especially common in older guinea pigs and are mainly found on their back and rump.
Do sebaceous cysts need to be removed?
While sebaceous cysts can become quite large, they often don’t cause discomfort for your pet. As a result, many owners choose not to treat them. However, certain cysts, especially depending on their location, can be bothersome to a guinea pig.
If a cyst is allowed to grow excessively large, it increases the risk of rupturing, which could create a substantial crater in the skin.
Guinea pig expert Peter Gurney recommends removing sebaceous cysts once they reach the size of a bean.
How are sebaceous cysts removed?
A veterinarian should perform sebaceous cyst removal, though some experienced rescue centres also undertake this treatment.
Typically, the area with the cyst is shaved, followed by the application of a cold spray to numb it—this process is known as cryothermic anaesthesia. A small incision is then made to lance the cyst, allowing the pus to be squeezed out. The area is flushed clean to ensure complete removal of cyst contents, and finally, an antibiotic spray is applied.
Cavy Central Guinea Pig Rescue demonstrates this procedure in several of their videos.
What should I do if a sebaceous cyst bursts?
If a cyst bursts, its contents should be gently squeezed out. Following this, the area should be cleansed with an antiseptic solution. Ensure the area remains clean as these cysts can become infected. If you’re unsure about handling the cyst, it is best that you make an appointment with your vet to deal with it.
If the cyst refills, surgical removal might be necessary, but this is often only considered if it’s causing discomfort to the guinea pig.
