Ringworm in Cats: Signs, Treatment and Cleaning

Quick answer

Ringworm is a fungal infection of the skin, hair and claws, not a worm. In cats it usually shows as patches of hair loss with scaly or crusty skin, often on the head, ears and front legs. It spreads easily to other pets and to people. A vet confirms it with tests and treats it with a combination of medicated washes or dips and oral medicine, usually for six weeks or more, while you clean the home to get rid of spores.

What ringworm is

The name comes from the ring-shaped rash it causes in people. The culprits are fungi called dermatophytes, which feed on keratin, the protein in hair, skin and nails. In cats the most common one is Microsporum canis.

Infection spreads by direct contact with an infected animal or person, and through spores on bedding, brushes, carriers, furniture and carpet. Those spores are hardy and can stay infectious in a home for many months.

Which cats get it

Any cat can catch ringworm, but it is most common in:

• Kittens, whose immune systems are still developing
• Long-haired cats such as Persians, which can carry spores in the coat while showing few or no signs
• Cats from crowded settings like catteries, shelters or busy breeding homes
• Older or unwell cats with weaker immune defences

Some cats are carriers: they look normal but still spread spores to people and other animals. That's one reason a single infected cat in a multi-cat home usually means testing everyone.

Signs to look for

Ringworm doesn't always look like a neat ring in cats. Watch for:

• Round or irregular patches of hair loss, often on the face, ears, head or legs
• Broken, stubbly hair
• Grey, scaly or crusty skin, sometimes looking like dandruff
• Redness, which may or may not itch
• Rough, brittle or misshapen claws
• More grooming or scratching than usual

Plenty of other conditions look similar, including flea allergy, mites, and overgrooming from stress or pain. Don't assume. Get it checked.

How vets diagnose it

• Wood's lamp: an ultraviolet light makes some infected hairs glow apple-green. Not every case glows, so a negative result doesn't rule it out.
• Microscope: looking at plucked hairs for fungal spores.
• Fungal culture: hairs and scale (often collected by brushing the coat with a sterile toothbrush) are grown in the lab. It's the most reliable test but can take up to three weeks.
• PCR: a faster DNA test, though it can pick up dead fungus and give a positive result after a cat is actually cured.

Treatment

Ringworm can clear on its own in a healthy cat, but that can take many months, during which the cat keeps shedding spores into the home and onto people. Treating it is the better choice.

Most vets use two approaches together:

1. Topical treatment to kill spores on the coat. This is often a lime sulphur dip or a medicated shampoo (such as one containing miconazole and chlorhexidine), applied to the whole body once or twice a week. Spot creams on single patches aren't enough because spores are spread through the coat.
2. Oral antifungal medicine to clear infection inside the hair follicles. Your vet will choose the drug and dose based on your cat's age and weight. Give it exactly as directed and for the full course; follow your vet's dosing even when the skin looks better.

Long-haired cats may need a gentle clip so the treatment can reach the skin. Your vet may advise doing it at home or at a quiet time so spores don't spread around the clinic.

How long does it take? Usually at least six weeks, sometimes much longer. The hair often regrows before the infection is gone. Vets usually repeat fungal tests every few weeks and consider a cat cured once results are negative, often two in a row. Stopping early is the commonest reason ringworm comes back.

With aggressive treatment, most cats are far less contagious after a few weeks, but keep up the precautions until your vet signs off.

Cleaning your home

Cleaning matters as much as medicine, because spores in the environment can reinfect your cat and infect people.

• Confine the cat to one easy-to-clean room (no carpet, few soft furnishings) during treatment, while still giving it company, play and a comfortable bed.
• Remove hair daily. Vacuum or wipe up loose hair, ideally with a vacuum that can be emptied straight into a sealed bin bag, and use disposable cloths.
• Wash bedding, throws and washable toys on a hot cycle, twice if heavily contaminated. Throw away items that can't be washed, like scratching posts with fabric covers, if they're heavily used.
• Disinfect hard surfaces after removing visible dirt. Diluted household bleach is widely recommended for floors and surfaces that tolerate it; ask your vet about the strength to use. Rinse and let surfaces dry before the cat goes back. Some veterinary disinfectants are also labelled for ringworm spores.
• Clean brushes, carriers, bowls and cat trees, or replace cheap items.
• Repeat regularly, ideally twice a week for deep cleans, until your vet says your cat is clear.

Protecting people and other pets

Ringworm is one of the commonest infections people catch from pets (see diseases you can catch from pets).

• Wear gloves and a long-sleeved top when handling or treating your cat, and wash your hands afterwards.
• Keep young children and anyone with a weakened immune system from cuddling the cat until it's cleared.
• See a doctor if you get an itchy, red, ring-shaped or scaly patch. It's usually easy to treat in people.
• Have other cats and dogs in the home checked. They may need treating too.

Buying or adopting a kitten

Ringworm is common in kittens from crowded homes. Look closely at the face, ears and paws for patchy hair or crusts and ask whether any animals there have had skin problems. Our guide on how to choose a healthy kitten covers what else to check.

When to see a vet

Book an appointment promptly if your cat:

• Has patches of hair loss, scaly or crusty skin, or broken hairs
• Has misshapen or crumbly claws
• Lives with a person or animal recently diagnosed with ringworm

See a vet sooner if your cat:

• Has sores that are weeping, smelly or spreading quickly, which can mean a secondary bacterial infection
• Is a young kitten, or is also off its food, losing weight or lethargic
• Isn't improving after several weeks of treatment

Go back for follow-up tests even if your cat looks fine, so you know the infection has truly gone.