Percy and Alex, 6 month old guinea pigs. Percy developed a rash.

Lisa has had their guinea pigs for five months now. Both guinea pigs are female, despite their names, and they seem to enjoy each other’s company. Lisa adores her pets, and the first thing she does when she comes back from school every day is to take them out of their cage to play for ten minutes.

Percy started to itch occasionally a few weeks ago, and a bald, reddened area appeared on her back, just above her tail. She stopped enjoying being picked up by Lisa, kicking and struggling rather than snuggling into her arms in her usual way. Both Percy and Alex were brought along to my clinic for a check up. Both guinea pigs seemed very healthy, and the only problem was Percy’s rash. She didn’t like it when I touched the area: it was obviously bothering her.

The most common skin disease to affect guinea pigs is caused by a microscopic mite that burrows into the skin. This mite usually affects the head, shoulders, back, and flanks of the guinea pig, but may spread to the entire animal. Once the mite has caused initial damage to the skin, secondary bacterial infections can occur. A mild rash can easily develop into raw, reddened skin that looks similar to a badly grazed knee after a fall in the school playground. Some affected animals just have a mild itch, nibbling the affected area gently from time to time. In other cases, the itching is so severe that some animals are almost driven demented by the itch, scratching at themselves furiously, and continually chewing at the sore areas. Rarely, they may even appear to have seizures because they become so overwhelmed with the severity of the itchiness. Percy just had a mild problem when I looked at her, but without treatment, she would have rapidly deteriorated.

The mite is diagnosed by taking a skin scraping, rubbing the edge of a scalpel blade on the skin to collect a sample of cells and debris from the skin surface. This is always done by vets if there’s doubt about the diagnosis, but when it’s very unlikely to be anything else, treatment may be without taking a skin scraping. It can be tricky – for vet, owner and guinea pig – to take a skin scrape from an uncooperative guinea pig. In Percy’s case, I decided to give her the usual treatment, and if she didn’t respond as expected, a skin scrape (and perhaps a biopsy) would have to be taken at a later stage.

Some guinea pigs may carry the mite, without showing any signs of itchiness or a rash, so I treated Alex as well. I also suggested that the guinea pig’s hutch was thoroughly cleaned out, to make sure that no mites were hiding there. We also discussed the guinea pigs’ diet, and it was good to hear that their nutrition was spot-on: they’re fed on standard guinea pig nuggets, supplemented with carrots, celery, parsley and grazing on grass. Guinea pigs are prone to Vitamin C deficiency which can aggravate skin disease, but with the extra greens that they were getting, there was no risk of this in Percy and Alex’s case. The two guinea pigs love fresh food, squeaking and chirruping excitedly whenever someone opens the fridge close to their feeding time.

Treatment for mites involves an injection of an anti-parasite drug once a week for three weeks. By the time they came in for the second injection, the rash had already cleared away.


Guinea pig skin disease is often caused by microscopic mites

Skin scrapings are needed to confirm this, but they’re not always needed

Treatment involves a series of injections that almost always cure the problem


  • Sarah says:

    Just a comment on diet – there was no mention of hay above which is concerning as guinea pigs’ diet should be at least 80% hay with only a very small amount of guinea pig nuggets plus a selection of vegetables. Fibre is crucial for gut and teeth health in hind gut fermentors!

    • petethevet says:

      Of course Sarah, and thanks for bringing this up. Diet is a really important part of skin health in Guinea Pigs.

Leave a Reply

Your email address will not be published. Required fields are marked *

Please note that I am unable to answer veterinary questions in comments. If you have questions or concerns about your pet's health it is always better to contact your vet.

Privacy | Terms and Conditions