Ringworm is an infection caused by a fungus that grows in the superficial layers of the skin, hair, or nails. The organism can also cause infection in dogs and humans. Cats may become infected either by direct contact with an infected animal or by exposure to a contaminated environment or object, such as grooming tools, clippers, or bedding. Spores are the infectious stage of ringworm and found in clusters around infected hairs, and may only be seen by microscopic exam. Spores can remain infectious in the environment for up to two years. Usually some degree of self trauma is required to enable a fungal infection like ringworm to develop. Long-haired cats and cats under one year of age seem to be predisposed.
The clinical signs of ringworm can vary. Most commonly, discrete roughly circular areas of hair loss, particularly on the head, ears, or extremities may be seen. The hair may be broken or lost, and the affected skin is often scaly and inflamed. However, ringworm may also look very similar to many other feline skin diseases. Hair loss is typically involved, but inflammation, scaling, and itchiness can be quite variable. Tentative diagnosis is often possible by ultraviolet Wood's lamp, but a microscopic exam of suspect hairs and/or fungal culture is usually preferred.
Treatment of ringworm includes addressing any predisposing skin conditions, as well as treating all pets in the home. Systemic therapy is typically needed using an oral antifungal product liquid known as Itraconazole. Topical therapy is often used as well, such as Malapet Medicated Shampoo. Since ringworm spores can survive for a long time in the environment, decontamination is often suggested by both physically removing the infected hairs from the environment, and using chemical agents to kill the fungal spores.