If you’ve been caring for cat colonies, barn cats, or fostering kittens, you’ve probably gotten some experience with ringworm by now. Ringworm and cats are often linked together in very negative ways.

There are many causes of ringworm and cats are only one of them. Cats are often blamed for it in people, horses, and other pets.

Ringworm sounds super scary, but it really isn’t. It is a common issue in outdoor cats, shelters, and especially kittens. So let’s learn what ringworm actually is, the causes of it, symptoms of it in cats, and the treatment options available.

Disclaimer: I am not a veterinarian. This article is for educational purposes only and should not be used to diagnose or treat any illness or disease. Please discuss any health issues regarding your pets or cat colony with your veterinarian.

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Ringworm is a fungal infection of the skin. It is not a worm or parasite. It is called ringworm because it can cause a circular red rash that is shaped like a ring. Not all infections will cause the circular rash, though.

Depending upon where the rash is located, it often has different names. Ringworm of the feet is often called athlete’s foot. Ringworm in the groin is called jock itch. Your fingernails and toenails can contract this fungal infection too and it won’t be called ringworm. But it is the same thing. If you want a full list of various names for these fungal infections, you can find them here.

Ringworm is called tinea or dermatophytosis in medical terms. Tinea corporis is the medical term for ringworm of the body, the most common type of fungal infection known simply as ringworm.

A barn cat with ringworm.

About 40 different species of fungi can cause ringworm. You heard that right. FORTY DIFFERENT KINDS! The most common class of fungi that cause skin infections are called Dermatophytes. These fungi obtain nutrients from the keratinized material of humans and animals, such as nails, hair, feathers, etc. This is why they infect the outer layer of the skin. But let’s not get too technical.

Depending upon where the infection is located, it could be called ringworm or it could be called athlete’s foot. That said, in cats, it’s just called ringworm no matter where it’s located.

Causes of Ringworm in Cats

Fungi thrive in moist, warm environments and common sources of fungal skin infections include locker rooms, tanning beds, skin folds, swimming pools, exercise machines, and even your garden soil!

Risk factors for contracting ringworm include using public showers, contact sports such as wrestling, excessive sweating, contact with animals, obesity, poor immune function, and poor hygiene. Children (and kittens) as well as those with a depressed immune system are most often infected.

Some species of dermatophytes are species-specific and only infect that species. Some species can infect a wide variety of animals and humans.

In cats, the species that is most often the cause of ringworm is Microsporum canis, which can infect cats and sometimes dogs, horses, and people. In fact, 98% of ringworm cases in cats are caused by this one species, according to the Merck Veterinary Manual. Other types of ringworm, such as the species that live in soil, can also affect cats and people.

Ringworm in cats can often be asymptomatic, which results in a carrier condition. This simply means that a cat can spread ringworm but has no symptoms of an infection. The cause of ringworm in cats is contact with infected animals, objects, or environments.

That said, ringworm might be contagious but it isn’t THAT contagious. It is not uncommon to only have one or two cats or kittens infected, while the rest of the household or colony shows no symptoms at all. That is because most adults (both human and cat) are often resistant to infection. But prolonged exposure increases the risk of infection in healthy adults.