Ringworm in Cats

The following content is intended to be informational. We do not assume responsibility or liability for patient care or outcome.

What is ringworm?

Ringworm is a fungal infection that affects the skin, hair and nails. It is highly contagious to not only other cats, but dogs and even humans! It is not an uncommon condition and any animal showing symptoms should be seen by a vet immediately to begin treatment. Animals with compromised immune systems, like kittens and senior cats can be particularly susceptible.


How is it spread?

Dermatophytosis (the medical name for Ringworm) is very contagious as infected spores are spread into the cat’s environment, including on bedding, furniture, toys, grooming tools, even carpeting and air vents. Ringworm can be spread by direct contact with an infected animal, or just by being exposed to the same environment.

Spores in the environment can remain infectious for up to 2 YEARS and can be difficult to kill.


The name “ringworm” is misleading in that it is not caused by any worms, but refers to the red “rings” that can appears on the skin. Lesions of ringworm can be localized areas of redness, with bald, flaky patches of skin in the center. These lesions will commonly appear on the cat’s head, legs, chest and back. Ringworm can sometimes appear more generalized over large portions of the body and is seen as patchy hair loss.  Not every animal will have the same symptoms, so diagnosis by a vet is needed if ringworm or exposure to ringworm is suspected.

In order to determine if a cat is positive for ringworm, a veterinarian may use the following tests:

  • Wood’s Lamp: Infected hairs will fluoresce under this lamp that emits ultraviolet light at a particular wavelength. However, only around 50% of cases show fluorescence, so another test is usually required.

  • Cultures: Skin and hair scrapings are taken to be used in a fungal culture. This test is reliable, however may take up to several weeks to get a positive or negative result.

  • Microscopic Examination or Biopsy: In a laboratory, a sample of hair and skin scrapings can be examined to determine if spores are present. However, the absence of dermatophytes does not rule out ringworm infection.


Once diagnosed, treatment is important to prevent the spread of the infection to other pets and humans. Your veterinarian will prescribe a recommended treatment based off of the severity of the infection, as well as taking into consideration any other skin conditions. Treatment may include oral medication, and/or topical treatment such as ointment or shampoo. Periodic rechecks of the fungal cultures and treatment of the cat’s environment will help eradicate the infection and keep it from reoccurring.

Cleaning house

A thorough cleaning should be done of the cat’s entire environment, it should also be repeated as the cat is going through treatment.  Cleaning and disinfecting products should be used that kill the spores, including products like All Stop or a 1:10 bleach and water solution. Make sure to read directions as most of these types of products must be left to sit on the surface for at least 5-10 minutes to be effective. Remember, bleach may cause discoloration or damage to some surfaces or fabrics (do not use chlorine-free bleach).

  • Bedding and Toys: Should be thoroughly cleaned or thrown away

  • Discard any item that is difficult or impossible to clean (carpeted cat trees)

  • Frequently vacuum the furniture, floors, vents, etc. and throw away the bag

  • Wear gloves and/or wash hands thoroughly after cleaning or handling pets

  • Restrict the infected pets to smaller areas or certain rooms to help minimize cleaning and chance of spreading the infection

  • Damp mopping or electrostatic cleaners (like Swiffer) will help clean floors

Treatment should continue on the recommendation of your veterinarian. Typically 2 negative cultures indicate that your cat has been successfully treated.