Ringworm in Dogs and Cats

Despite its name, ringworm is caused by a fungus rather than a worm. Ringworm infection can be transmitted through direct contact with an infected animal or fungus spores left behind by that animal. Ringworm spores survive for quite some time after being shed, so any place that an infected animal has recently visited carries a risk of infection.

Many healthy adult cats and dogs are somewhat resistant to ringworm. Animals most vulnerable to ringworm infection are:

    • Under one year of age or elderly
    • Suffering from diseases
    • Free-roaming outdoor pets
    • Malnourished
    • Under stress
    • Afflicted with viral infections or parasites

Certain purebreds such as Persians are also more susceptible to ringworm infection.

Ringworm Symptoms in Pets

Symptoms of ringworm in pets include:

    • Patchy hair loss
    • Itchy skin
    • Scratching, particularly around the ear area
    • Small, round, scaly skin lesions that are visible because no hair grows over them
    • Malformed claws if the infection attacks the nails

Ringworm Treatments

If you suspect that your cat or dog has ringworm, take him to a veterinarian immediately for diagnosis and treatment. If ringworm is confirmed, the veterinarian may also check for underlying conditions that may have made your pet more vulnerable to ringworm infection.

Ringworm treatments include:

    • Shampoos
    • Lime sulfur dips
    • Topical medications
    • Trimming or shaving the fur (though some vets do not recommend shaving when treating ringworm, as it may actually spread the fungus)

Lime sulfur dips smell terrible and may temporarily dye the animal’s fur a yellowish colour, but they are particularly effective against ringworm. In severe, resistant cases, oral medication may be prescribed.

There is a ringworm vaccine that prevents the development of lesions, but it may not actually prevent the infection. This means that the dog or cat may be a carrier, infecting other members of the household without actually showing symptoms. Also, a flea pill called Program is recommended by some veterinarians for ringworm, but others claim that it is ineffective or unproven, which suggests that more research is required before the experts will develop a consensus on this product’s efficacy for ringworm.

Many studies indicate that ringworm will usually go away on its own after a number of months. However, given that it’s an infectious condition that can be transmitted to other household pets and humans, seeking veterinary treatment is recommended rather than simply waiting it out.

There are many home remedies for ringworm that can be found on the Internet, and a lot of these are dangerous for cats and dogs. Don’t try a home remedy without first consulting a veterinarian to make sure that it’s safe.

Humans Can Catch Ringworm from Pets

Humans, particularly children, the elderly, and those with reduced immune function due to medical conditions or treatments, can catch ringworm from cats, dogs, and other pets. The primary symptom in humans is a ring of itchy, red skin. To avoid catching ringworm from an infected pet, wear gloves whenever handling the animal and if any part of your skin comes in contact with the infected pet, wash it immediately.

How to Kill Ringworm Fungus Spores Around the House

Infected animals will shed spores around the house until the fungus on the pet’s skin has been killed, and spores that were shed before treatment was implemented may still be lying around, so disinfecting the home is an important aspect of prevention. If possible, confine the infected cat to one room until he is pronounced cured by a veterinarian and clean and disinfect that room regularly.

For the overall household cleanup, rather than sweeping, which tends to just spread the spores around:

    • Vacuum and mop all floors.
    • Vacuum and steam clean all carpets, furniture, and drapes.
    • Discard vacuum bags immediately after use.
    • If possible, have furnaces and heating and cooling ducts professionally vacuumed.
    • Use a bleach solution (1 part bleach, 10 parts water) on any surface that can be safely bleached, leaving the solution on for 10 minutes or more.
    • Disinfect all grooming tools, carriers, and pet bedding.

Other Causes of Itching and Fur Loss

A veterinary check-up is required to diagnose ringworm, as there are other conditions that can cause itchiness and fur loss. Symptoms similar to those of ringworm may be caused by other infections, demodectic mange, flea infestation, allergies, or psychogenic alopecia (over-grooming and plucking out fur due to stress).

For more cat articles, see the main Cats page. For more dog articles, see the main Dogs page.

This article is provided for informational purposes only and is not intended as a substitute for veterinary consultation and care.


    • Davis, Karen Leigh. (1999). American Shorthair Cats. New York: Barron’s Educational Series, Inc.
    • Mar Vista Animal Medical Center. (n.d.). “Ringworm.” MarvistaVet.com.
    • Veterinary & Aquatic Services Department, Drs. Foster & Smith. (2011). “Ringworm in Cats” and “Ringworm in Dogs.” PetEducation.com.

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