What is ringworm?
Updated By PetymFacts checked against official sources on
Quick answer
Ringworm is a fungal skin infection, not a worm. In cats about 98% of cases are caused by the fungus Microsporum canis, and about 70% in dogs. It causes round patches of hair loss and scaly skin, spreads easily from pets to people, and its spores survive on shed hairs in the home. Cats can carry it without any signs.
Also called dermatophytosis, Microsporum canis, fungal skin infection, tinea.
Key facts
- Ringworm is caused by a fungus, not a worm, and spreads easily between people and from pets to people. US Centers for Disease Control and Prevention
- About 98% of ringworm cases in cats are caused by Microsporum canis. Merck Veterinary Manual
- Cats can carry the fungus on their skin without any visible reaction. Cornell University College of Veterinary Medicine
- Broken hairs carrying spores are an important source of spread, so the home needs thorough cleaning. Merck Veterinary Manual
- In eastern India, ringworm fungi were found on 21% of samples from healthy pet dogs and 37% from healthy pet cats. Iranian Journal of Veterinary Research (2016)study
- In and around Kolkata, infections were more common in the rainy season and in pet owners in contact. Veterinary World (2015)study
What does ringworm look like on a pet?
The classic sign is a bald, scaly, crusted patch with broken hairs, most often on the face, ear tips, tail and feet. Some cats get small, itchy bumps instead. Kittens are most likely to be infected, and kittens and long-haired cats may have more persistent, widespread infections. Some cats carry the fungus with no sign at all.
Ringworm looks like several other skin problems, including demodectic mange and allergies, so a vet confirms it with an ultraviolet lamp, a microscope check of hairs or a fungal culture, the most accurate test, which can take up to 3 weeks.
How do you stop ringworm spreading at home?
Treat the pet and the home together, and protect the family.
Do
- Take the pet to the vet and follow the full treatment plan, including rechecks. US Centers for Disease Control and Prevention
- Wear gloves when handling an infected pet, and wash your hands afterwards. US Centers for Disease Control and Prevention
- Vacuum the areas of the home the pet uses, often. US Centers for Disease Control and Prevention
- Clean the pet's surroundings thoroughly; Merck suggests a dilute bleach solution. Merck Veterinary Manual
Don’t
- Do not let children cuddle an infected pet until the vet says it is clear. US Centers for Disease Control and Prevention
- Do not stop treatment early because the patches look better; ask the vet when to recheck.
- Do not rely on a vaccine: WSAVA lists Microsporum canis vaccines as not recommended. WSAVAstudy
- Do not share grooming tools or furniture between an infected pet and others; they carry spores. Merck Veterinary Manual
Why does ringworm rise in the Indian monsoon?
Fungi like warmth and moisture. A Kolkata study of dogs and cats with suspected ringworm found infections more common in the rainy season, and found the same fungi in pet owners who were in contact with them. A study of healthy pets in eastern India found the fungi on more than a third of cat samples and a fifth of dog samples, a reminder that a pet can look fine and still carry it.
Keep pets dry after wet walks, wash bedding regularly in the monsoon, and see a vet early for any patch of hair loss.
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Questions owners ask
Can I get ringworm from my cat or dog?
- Yes. Ringworm spreads easily from pets to people, and in a Kolkata study owners in contact with infected pets were also infected. Wear gloves to handle an infected pet, wash your hands and see your doctor if you develop a rash.
Is ringworm a worm?
- No. Despite the name, ringworm is a fungal infection of the skin, hair and claws. In cats about 98% of cases are caused by the fungus Microsporum canis, which also causes about 70% of cases in dogs. Deworming medicines do nothing for it; a vet treats the fungus.
How long does ringworm last in pets?
- It varies. Merck notes some infections clear on their own, while treatment speeds healing and cuts spread; kittens and long-haired cats may have more persistent infections. Spores on broken hairs can keep reinfecting a pet, so cleaning the home is part of the cure. Your vet decides when it is cleared.
Can a pet have ringworm without showing it?
- Yes. Cornell notes that the fungus can live on a cat's skin without causing any reaction, and an eastern Indian study found ringworm fungi on many healthy-looking pets. Such carriers can still pass it to people and other pets, which is why a vet may test all animals in the home.
Keep reading
Related terms
More in vaccines and parasites
- BabesiosisBabesiosis is a disease of dogs caused by Babesia, tiny parasites that live in and destroy red blood cells. It is spread mainly by ticks, and in India one species, Babesia gibsoni, also spreads through dog fights and blood transfusions. Signs are anaemia with pale gums, weakness, jaundice and red or brown urine. Dogs that recover can relapse.
- Booster vaccineA booster is a repeat dose of a vaccine that tops up or confirms a pet's protection. Puppies and kittens get a booster at about 26 weeks after their first course. After that, modern core vaccines for distemper, parvovirus and panleukopenia protect for years, while leptospirosis, kennel cough and most killed vaccines need a booster every year.
- Brown dog tickThe brown dog tick, Rhipicephalus sanguineus, is the most common tick on dogs in the tropics, including India. Unlike most ticks it lives and breeds indoors, in homes and kennels, as well as outdoors. It spreads ehrlichiosis and one form of babesiosis, the infections Indian owners call tick fever, so tick control is needed all year.
- Core vaccinesCore vaccines are the vaccines every dog or cat should have, wherever it lives, because they protect against widespread, serious diseases. For dogs they cover distemper, adenovirus and parvovirus; for cats, panleukopenia, herpesvirus and calicivirus. In India rabies is core for both, and WSAVA also treats leptospirosis vaccine as core for dogs where the disease is endemic.
- DewormingDeworming is giving a pet medicine, chosen by your vet, to kill intestinal worms such as roundworms, hookworms and tapeworms. Puppies can be born with roundworms and catch more from their mother's milk, so deworming starts in the first weeks of life. Some dog and cat worms can infect people, especially children, so regular deworming protects the family too.
- DHPPi vaccineDHPPi is the combined core vaccine for dogs printed on many Indian vaccine cards. The letters stand for distemper (D), hepatitis from canine adenovirus (H), parvovirus (P) and parainfluenza (Pi). DHPPiL adds leptospirosis (L). It is the same vaccine group that US cards call DHPP or DA2PP, and puppies start it at 6 to 8 weeks.
- EhrlichiosisEhrlichiosis is a disease of dogs caused by Ehrlichia canis, a bacterium carried by the brown dog tick. Signs appear 1 to 3 weeks after infection: fever, dullness, bleeding such as nosebleeds or bruising, and enlarged lymph nodes. Some dogs seem to recover but carry the infection silently and later develop a severe chronic form.
- Flea and tick preventionFlea and tick prevention means regularly protecting a pet from these parasites with a product your vet recommends, plus checking the coat and treating the home. Tropical guidelines say dogs and cats in places like India should be protected all year, including indoor pets. Use products licensed for the species, and never put a dog product on a cat.
- FleasFleas are small, wingless, blood-feeding insects. The cat flea, Ctenocephalides felis, is the most common flea on dogs and cats worldwide, and the main flea on dogs studied in India. Fleas cause itching, flea allergy, tapeworm and, in heavy infestations, anaemia in puppies and kittens. Most of the flea life cycle happens in the home.
- FVRCP vaccineFVRCP is the core combined vaccine for cats. It protects against feline viral rhinotracheitis (herpesvirus), calicivirus and panleukopenia. Indian cards often show a brand name from the vial sticker instead, such as Tricat. Kittens start at 6 to 8 weeks, with doses every 2 to 4 weeks until 16 weeks or older, then a booster at about 26 weeks.
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Sources
Each source was opened and read on the date shown. How Petym checks its sources
- US Centers for Disease Control and Prevention: What causes ringworm (opens in a new tab)
- Merck Veterinary Manual: Ringworm (dermatophytosis) in cats (opens in a new tab)
- Cornell University College of Veterinary Medicine: Ringworm: a serious but readily treatable affliction (Cornell Feline Health Center) (opens in a new tab)
- US Centers for Disease Control and Prevention: Ringworm prevention (opens in a new tab)
- Merck Veterinary Manual: Ringworm (dermatophytosis) in dogs (opens in a new tab)
- Iranian Journal of Veterinary Research (2016): Detection of dermatophytes in healthy companion dogs and cats in eastern India (opens in a new tab)
- Veterinary World (2015): Detection and characterization of zoonotic dermatophytes from dogs and cats in and around Kolkata (opens in a new tab)
- WSAVA: 2024 guidelines for the vaccination of dogs and cats (WSAVA Vaccination Guidelines Group, Journal of Small Animal Practice) (opens in a new tab)