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David Adams
Department of Health Sciences, AASU


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Cats and Ringworm: The Ugly Truth

by David Adams

January 01, 2014

What is Ringworm?

First, "ringworm" is not a worm. Sorry to burst your bubble, but "ringworm" is caused by a fungus not a worm. The three primary types are Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes, the first two of which are especially common in dogs and cats. Ringworm is quite contagious and presents as patchy, roundish, reddish areas on the skin. It is easy to spot because the hair has disappeared from these patches. Moreover, ringworm can spread easily to humans and other pets.

What Are the General Symptoms of Ringworm?

Ringworm in cats presents as skin lesions, typically on the head, ears and forelimbs. It produces flaky, hairless patches that often are reddish in the middle. Severe cases can spread over the entire body.

How Do Cats Get Ringworm?

Cats contract ringworm either directly (via contact with an infected animal) or indirectly (via contact with fomites such as contaminated bedding). Ringworm spores can survive in the environment for more than a year.

Which Cats Are Prone to Ringworm Infection?

Any cat can develop ringworm, but the very young, very old, and immunocompromised are especially prone to infection. Longhaired and immunocompromised cats are also more susceptible. Ringworm can quickly spread in shelters or other crowded environments; warm and humid conditions tend to promote ringworm infections.

What Should I Do If I Think My Cat Has Ringworm?

It is important to see your vet for an accurate diagnosis. Moreover, this condition can spread easily to humans as well as other pets. It is a good idea to quarantine your cat immediately until a vet can confirm a diagnosis. Wash your hands thoroughly after touching your cat.

How Is Ringworm Diagnosed?

Some cats show little or no symptoms of ringworm. As such, a definitive diagnosis of ringworm is rarely made just by simply examining the skin. A veterinarian may use an ultraviolet light (e.g., a Wood’s Lamp) to diagnose ringworm. (The lesion will glow under the UV light.) He or she may examine skin samples under the microscopic as well.

How Is Ringworm Treated?

Treatment depends on the severity of the ringworm infection. The veterinarian may prescribe a shampoo or ointment with anti-fungal, oral medications. In some cases, however, he or she may prescribe oral medications are necessary. In order to eradicate this fungus completely, treatment may need to continue for several months with periodic fungal cultures from time to time. Treatment of the cat’s environment is necessary in order to prevent relapse of infection.

How Can I Prevent Ringworm from Spreading?

If your veterinarian has diagnosed your cat with ringworm, he or she will explain what you must do to prevent the fungus from spreading to other pets—and to you, for that matter. Nevertheless, keep in mind that if you have other pets, it is likely your veterinarian may recommend several regimens. These may require that you bathe your pets with a medicated rinse or shampoo, launder the infected animals’ bedding and toys with an anti-fungal disinfectant, discard things such as carpeted cat-trees that is impractical to disinfect, and vacuum frequently to rid the floor of infected hairs and skin cells. Finally, remember to wash your hands thoroughly after handling or bathing your cat.

What Can Happen if Ringworm Remains Untreated?

Untreated ringworm lesions can spread over large areas of an animal’s body. Such infestations may result in hair loss and skin infections.

What Types of Animals Can Contract Ringworm?

All mammals (people, too) can get ringworm. Although it is most common in cats, it also occurs in a variety of other animals such as rabbits, dogs, chinchillas and hedgehogs.

Ringworm in General

Cats, not least longhaired cats, often have multiple ringworm lesions. Dogs, however, typically have but one. (In dogs, ringworm is most common in younger ones.) Cats that recover from ringworm often remain "healthy carriers" that show no signs of infection. When handling infected pets, it is always best to wear protective gloves.

What Are The Symptoms Of Ringworm?

Ringworm typically produces circular patches of broken hair that appear as ring-like coils. These areas typically heal at their centers and grow darker than normal hair. A band of inflamed, reddened skin with short hair is also broken and short. The most common areas for ringworm include the face, ear tips, tail and paws.

How Does Your Pet Contract Ringworm?

Ringworm fungi (e.g., Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes) do not penetrate normal skin. The spores are transmitted into a scratch or scrape on the same or different animal. The usual source is a carrier pet that shows no signs of the disease. Other common modes of transmission include contaminated grooming supplies and hair clippers. Not all exposed pets will develop the disease, however.

How is Ringworm Diagnosed?

Some cases of ringworm are so "textbook" that diagnosis can be done by appearance alone.

How is Ringworm Treated?

Infected pets first should be segregated from those that appear asymptomatic. Treatment usually includes Betadine scrubs, ketoconazole ointment, and grisiofulvine tablets. Grisiofulvin, however, can be toxic in cats who are pregnant, immunocompromised, or suffer from feline leukemia. Safer options include itraconazole, terbinafine, and fluconazole.

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