Ringworm in Cats: Symptoms, Treatment, and Is It Contagious to Humans?

Despite the name, ringworm has nothing to do with worms. It's a fungal infection, and in cats it often shows up first as small patches of hair loss or crusty skin around the paws and claws before spreading anywhere else. It's also one of the few common cat conditions that can genuinely jump to the humans in the house.

What ringworm actually is

Ringworm, or dermatophytosis, is caused by fungi that infect the outer layer of skin, hair, and claws. In cats, about 98% of cases come from a single species, Microsporum canis, according to the Merck Veterinary Manual. It's highly contagious between animals and spreads easily through direct contact or contact with contaminated bedding, carpet, or grooming tools.

Why the paws and claws are often affected

Ringworm classically causes circular patches of hair loss with scaly or crusty skin, most often on the face, ears, tail, and paws. International Cat Care notes that the claws themselves can become infected too, leading to a rough, distorted, or crumbly texture as the nail grows, a form of the infection that's easy to mistake for an unrelated nail problem if the more typical skin patches aren't obvious yet.

The hidden-carrier problem

Not every infected cat looks sick. The European Advisory Board on Cat Diseases (ABCD) notes that some cats, particularly longhaired breeds, carry infected hairs and spread spores to other animals and people without ever showing visible lesions themselves. Combined with the fact that these fungal spores can remain infectious in the environment for many months, this is part of why ringworm spreads so efficiently through shelters and multi-cat households.

How it's actually diagnosed

A vet can't reliably diagnose ringworm by appearance alone. A Wood's lamp (a UV light some infected hairs glow under) catches only about half of cases, so a proper diagnosis usually involves a fungal culture or PCR test on a hair or skin sample, according to the UC Davis School of Veterinary Medicine. Culture results can take one to three weeks, which is part of why vets often start treatment on a strong suspicion before results come back, especially in a kitten with classic-looking lesions.

Treatment and preventing spread

Treatment typically combines an oral antifungal (such as itraconazole) with a topical treatment like lime sulfur dips or an antifungal shampoo, applied over several weeks rather than days. Because spores contaminate the environment so readily, thorough cleaning, vacuuming, and washing of bedding are just as important as treating the cat directly. Cats being treated are usually kept away from other pets and people in the household until follow-up cultures come back clear, since visible improvement in the skin doesn't necessarily mean the cat has stopped shedding spores.

Frequently asked questions

Can I catch ringworm from my cat?
Yes, it's zoonotic, and people, especially children, can develop circular, itchy skin lesions from contact with an infected cat or contaminated surfaces. Washing hands after handling a cat with suspected ringworm is a reasonable precaution.

Is ringworm more common in kittens?
Yes, kittens and young cats are more commonly affected, likely because their immune systems are still developing, which is part of why it's frequently seen in shelter and foster settings with multiple kittens.

How long does treatment usually take?
Most cases take several weeks to a couple of months to fully clear, confirmed by a negative follow-up fungal culture rather than just the skin looking better.

Sources

• Merck Veterinary Manual, "Ringworm (Dermatophytosis) in Cats"
• International Cat Care, "Ringworm in Cats"
• ABCD (European Advisory Board on Cat Diseases), "Guideline for Dermatophytosis, Ringworm in Cats"
• VCA Animal Hospitals, "Ringworm in Cats"
• UC Davis School of Veterinary Medicine, "Ringworm in Cats (Dermatophytosis)"

This article is for general information and isn't a substitute for advice from your own veterinarian, who can properly diagnose and treat suspected ringworm in your specific cat.