Guinea pig ringworm: Symptoms, treatment, and whether you can catch it

• Ringworm is a fungal skin infection, not a worm. In guinea pigs, it usually starts as bald, scaly patches on the face, around the nose, eyes, and ears.
• Ringworm in guinea pigs can look just like mites, and the treatments are different, so a veterinarian needs to confirm which one it is.
• Ringworm can spread to people and other pets, so wash your hands after handling, clean the cage thoroughly, and finish the full course of treatment.

If your guinea pig has a bald, scaly patch, it might be ringworm. Guinea pig ringworm usually shows up on the face, around the nose, eyes, and ears. The good news is that it’s treatable.

Ringworm can spread to people too, so if you’re worried about a patch right now, talk to a Vetster vet online today. The rest of this guide covers how to recognize guinea pig ringworm, how it’s treated, and what to do about the rest of your household.

Despite the name, ringworm is not actually a worm. It’s a fungal skin infection, also called dermatophytosis.

In guinea pigs, ringworm is usually caused by a fungus called Trichophyton mentagrophytes or Trichophyton benhamiae. Microsporum canis is a less common cause. These fungi feed on keratin in the skin, hair, and nails. The infection can cause hair loss and flaky, crusty skin.

Guinea pigs can carry the fungus without showing any signs. A carrier that looks completely healthy can still pass it to other guinea pigs or to people. This is one reason ringworm can appear in a household with no obvious source.

Ringworm on guinea pigs usually begins around the nose, eyes, ears, and forehead. Look for:

• Patches of hair loss with a roughly circular shape, though they aren’t always the perfect ring the name suggests
• Dry, flaky, or scaly skin inside the patch
• Inflamed edges, with redness, crust, or scabs

Some guinea pigs scratch at the patches, while others barely react at all. This is one way ringworm differs from mites, which usually cause intense itching.

As it progresses, ringworm can spread along the neck and shoulders and down the back. The patches may join up, and the skin can thicken. Scratching the area raw can lead to a secondary bacterial infection.

Guinea pig hair loss and flaky skin can have several causes that look alike. Ringworm, mites, bacterial skin infections, hormonal conditions such as ovarian cysts, and barbering between cage mates can all cause patchy areas of fur loss.

Mite infestations tend to affect the back, rump, and shoulders, and cause severe itching. Ringworm often starts on the face and produces circular, crusted patches that may or may not itch. That’s a useful guideline, but not a way to diagnose, especially since guinea pigs can have both at once.

Treatments for ringworm and mites are different, so speak to your vet first to confirm which one it is. An antiparasitic, the type of medication used for mites, will do nothing to treat ringworm. An antifungal will do nothing to treat mites. Save time by treating the right condition and prevent it from spreading to cage mates, and with ringworm, to other pets and people in the house.

How vets diagnose ringworm

Ringworm is usually confirmed by taking a fungal culture. PCR (polymerase chain reaction) testing is also available and faster, since a fungal culture can take a few weeks to produce results.

Looking at plucked hairs under the microscope can sometimes show the fungus, but it’s not the most reliable test. A Wood’s lamp, which is a type of ultraviolet light, is not reliable for guinea pig ringworm either, because Trichophyton mentagrophytes doesn’t glow the same way some strains of Microsporum canis can. A vet can help you understand if testing is needed for your guinea pig’s skin. Talk to a Vetster vet about your guinea pig’s symptoms and what to do next.

Yes. Ringworm is zoonotic, meaning it can pass between animals and people. In people, ringworm typically shows up as red, scaly patches on the hands, arms, face, or neck. They are often itchy, and sometimes take the classic ring shape with a clear center.

Children are commonly affected, since they tend to hold guinea pigs on their laps and close to their faces. Anyone with a weakened immune system is also at a higher risk of infection.

While your guinea pig is being treated:

• Wash your hands thoroughly after contact with your guinea pig, their cage, or anything inside it, like bedding, bowls, hides.
• Wear disposable gloves when applying topical treatment or cleaning their cage.
• Keep young children and anyone with a weakened immune system from handling your guinea pig until your vet confirms the infection has cleared.
• Keep other pets away from your guinea pig and their cage until the infection clears.
• Remove and wash any clothing that has been in contact with your guinea pig.
• Avoid letting your guinea pig sit against your neck or face.
• See your own doctor if a scaly patch appears on your skin, and let them know your guinea pig is being treated for ringworm.

Ringworm is not a reason to panic or rehome a guinea pig. When people catch ringworm from a pet, it’s usually straightforward to treat and recover from. Getting a proper diagnosis and starting treatment is what matters, so book a vet visit rather than waiting to see if it clears up on its own.

Treating ringworm in guinea pigs could take several weeks, sometimes longer. A vet will usually combine two or three approaches:

• A topical antifungal applied to the affected areas
• Oral antifungal medication for more widespread or stubborn cases
• Environmental decontamination

Common antifungals include itraconazole and terbinafine. Your vet will decide which form and dose is right for your guinea pig.

Medication safety for guinea pigs with ringworm

• Griseofulvin, an older antifungal that’s sometimes still prescribed, can cause birth defects and should never be given to a pregnant guinea pig.
• Never use antifungal products made for people or other animals, including a leftover prescription from another pet, unless your vet directs you to.
• Hydrocortisone cream, a staple in many first aid kits, suppresses the skin’s local immune response and can make a fungal infection worse.
• Triple antibiotic ointment won’t help either, since antibiotics don’t work on fungi.

Cleaning your guinea pig’s environment

Fungal spores can survive in the environment for months, sometimes longer. To decontaminate:

• Thoroughly clean the cage.
• Discard all bedding.
• Wash or replace hides, tunnels, and any fabric items.
• Vacuum the surrounding area to remove shed hairs, which carry spores.

This is an easy step to skip, but it’s what keeps ringworm from reinfecting your guinea pig or your household.

If you have more than one guinea pig, your vet may want to test or treat all of them, since ringworm is contagious and guinea pigs can carry it without showing any symptoms.

Finish the full course

Finish the entire course of medication, even if your guinea pig looks better. Guinea pigs often look much better before the infection is actually cleared, and stopping early can take you right back to the start. Book an online vet appointment for guidance on ringworm treatment for your guinea pig.

Ringworm is typically not an emergency, and a virtual Vetster appointment is a good place to start. A vet can look at the lesions, talk through what they might be, and tell you whether testing is needed.

Take your guinea pig to a vet in person right away if they:

• Stop eating (see what to do if your guinea pig is not eating)
• Become lethargic
• Have lesions covering a large area of their body
• Have raw, weeping, or badly infected-looking skin

Those signs can point toward systemic illness or a secondary bacterial infection, and both need a hands-on exam.

Ringworm lesions can be sore, not just itchy. Guinea pigs hide pain well, so a guinea pig who is hunched, reluctant to move, or unusually quiet should be seen by a vet. Here are other signs your guinea pig is sick.

Ringworm is an infectious disease, and there’s no way to make a guinea pig immune to it. Stress and poor conditions make ringworm more likely, so husbandry, or the daily care, diet, and living space, is where you have the most control.

• Quarantine any new guinea pig for at least 3 to 4 weeks, and keep a close eye on their skin before introducing them to other guinea pigs.
• Keep their cage clean and dry, and avoid overcrowding.
• Keep stress low, since a stressed guinea pig is more susceptible to ringworm.
• Wash your hands between handling different guinea pigs, especially if one is being treated for ringworm.
• Weigh and check your guinea pig regularly, parting their fur over their back and around their face so you can spot a patch when it’s small.

Young guinea pigs, older guinea pigs, and any guinea pig recovering from another illness are the most vulnerable.

Ringworm in guinea pigs is a treatable fungal infection, but it’s not one to wait out. It spreads to other guinea pigs and people, and it looks like other skin issues, like mites.

If your guinea pig has a bald patch with flaky or crusted skin, especially on their face, have it identified by a veterinarian so you can start the right treatment. Commit to the full course of medication and clean their environment as well. It takes patience, but ringworm does clear. If you’re not sure what you’re looking at, a Vetster vet can help you figure out what you’re seeing.