Ask the Vet: Ringworm

2004

Our shelter is a small rescue organization that primarily houses cats in foster care. We contract with a local veterinarian for assistance with spaying and neutering, and to a smaller degree with medical care. We spend a lot of our operating budget on veterinary care. We are having a problem with ringworm and would like to know more about how to handle this.

Thank you.

Answer:

Treatment, control and prevention of ringworm (feline dermatophytosis) in rescue foster care is complicated, especially if cats are housed together. As you may already know, ringworm is a fungal disease that is highly contagious, especially to young and immune compromised animals. It is also contagious to humans. In most cases it is a treatable condition, however the treatment of ringworm can be time consuming and potentially costly. A foster care environment can make control and prevention of ringworm even more complicated, since foster care usually involves caring for the cat or kitten in someone's home.

Learning to identify ringworm lesions and the animals that have them is the first step in treating, controlling and preventing ringworm. Ringworm lesions are typically circular areas of hair loss with or without broken hairs and crusty or scaling skin. Ringworm can also cause infection of the claws and nail beds. In a multi-cat environment like a shelter or rescue, it's important to get a definitive diagnosis by culture due to ringworm's highly contagious nature. (Most veterinary practices can help you with this.)

The next important step is to isolate the animal in an area that can be regularly disinfected. Isolation should begin as soon as an animal is suspect. If any animals were exposed to the suspected animal, they should be quarantined in a separate area that can be regularly disinfected for at least three weeks, during which they can be monitored for ringworm lesions.

Most culture tests for ringworm can take three to ten days to show a positive result. If a culture result comes back positive, topically treat the infected cat with an antifungal rinse. Ideally the cat should be dipped twice a week until the lesion is healed. Clipping the cat's hair has also been recommended to help reduce the spread of the organism into the environment and aid in the healing process. If the cat has more extensive lesions or other health related issues, putting the cat on systemic therapy may be considered. Systemic therapy should be used in conjunction with topical therapy for a more timely response.

Treatment can take six to twelve weeks or longer, depending on the overall health and well being of the cat. A cat must have three consecutive negative cultures, performed at least two to four weeks apart, before it can classified as "cured."

Controlling ringworm in a contaminated, multi-cat shelter or foster home environment depends on whether or not it is feasible to clean the environment thoroughly. Ringworm spores are tiny, microscopic organisms and can easily disseminate in a home environment. Cleaning all surfaces with an appropriate cleaning agent will help minimize the number of contagious spores. Since disinfecting a home contaminated with ringworm is so complicated, it is recommended that foster homes affected with ringworm use caution when fostering at-risk animals (i.e., kittens, FeLV and FIV positive cats, and/or cats undergoing antibiotic therapy).

Ringworm undeniably can be devastating. Establishing a plan of action prior to an outbreak is always helpful and highly encouraged. Educating staff and volunteers on what ringworm lesions look like and employing good treatment, isolation and quarantine practices will help minimize the spread of ringworm to other animals. Understanding which cleaning agents are more effective at killing ringworm spores and implementing good cleaning practices will further minimize contamination. For more information on ringworm in shelters, see the U. C. Davis School of Veterinary Medicine's Maddie's Shelter Medicine website at: http://www.sheltermedicine.com/portal/is_ringworm.shtml#top3.

I hope this helps. Good luck!

Laurie Peek, DVM