Your Dog Has Ringworm: What To Do Now

Although the name often misleads pet owners into thinking a worm has invaded their pet’s bodies, ringworm is actually a fungus that can affect the hair, skin and nails. This fungus can lead to circular patterns of hair loss and red, scabby bumps. Before you introduce another pet into your home, knowing the facts about ringworm and how to prevent the skin condition from spreading is crucial. 

Dermatophytes, fungi that feeds on protein in the skin, hair and claws, is the agent of ringworm. Infections are transmitted by contact with infected hairs from another infected pet in the environment, or through bedding, grooming tools, and even fleas. The fungus can be passed between animals and humans, but young and elderly people are more susceptible to developing the infection. Those with weak immune systems are also more prone to ringworm.

Dr. Adam Patterson, clinical assistant professor and chief of dermatology at the Texas A&M College of Veterinary Medicine & Biomedical Sciences, explains the signs of ringworm. “Clinical signs of ringworm may include excessive shedding, broken hairs, patchy or circular areas of hair loss, dander, scabs, red bumps and occasionally deep-seated nodules,” he said. “Some animals, especially cats, may be carriers of ringworm with no clinical signs. Diagnosis is based on history, clinical signs, fungal culture, and possibly skin biopsy. Fungal culture is the gold standard in making a diagnosis, but it may take up to three weeks for fungal growth to appear.”

Although the name often misleads pet owners into thinking a worm has invaded their pet’s bodies, ringworm is actually a fungus.

Treatment for infected animals includes limiting their exposure to other animals and people. Since it is common for some pets to be asymptomatic, all animals in an infected household should be treated and tested for the skin condition. “Therapy is directed at killing fungus on the animal(s) and decontaminating the environment. Unfortunately, dermatophyte-infected hairs can remain infective for up to several months, necessitating environmental clean-up of shed hairs,” Patterson explained. “If people in the household have ringworm-suspicious lesions, then consultation with a physician is recommended.”

Limiting the infected pet to other animals and people can be effective in preventing the spread of ringworm, but anti-ringworm treatments are required to eliminate the infection at its source. Shampoos, lotions, sprays, dips and systematic therapy can all be prescribed to a ringworm-infected pet. If the animal is long-haired, clipping the coat can allow better contact with topical medicine and will remove infected hairs before they shed into the environment.

Besides treating your pet for ringworm, decontamination of the environment is essential to prevent further spreading of the fungus. Isolating your pet in an easily cleaned room (no carpet) is the first step in decontaminating your home. Wash all clothing that has touched the animal, as well as destroy or thoroughly disinfect all collars, bedding, blankets, scratching posts, cat trees and grooming aids, if possible. Disposable dusting sheets and lint rollers can be effective in capturing loose hairs in the environment, and it is also recommended to launder exposed fabrics and pet bedding by washing twice in cold water with detergent. Thoroughly vacuuming rugs and draperies every one to two days will also prevent the buildup of infected hair. Disinfectants like Lysol and a Clorox mixture can be sprayed on tile floors, windowsills, vehicles the infected pet rode in, countertops and any other non-porous surface.

“The goal of therapy is to achieve two to three negative consecutive fungal cultures one to two weeks apart. Unfortunately, this usually requires at least several weeks of therapy,” said Patterson. “The risk of re-infection for a single pet is relatively low if they live indoors and the environment is cleaned thoroughly. When adding a new pet to the household (especially cats), one should have the animal examined by a veterinarian and consider having a ringworm culture performed before bringing the pet into the family’s living quarters.”

Ringworm is contagious to both owners and pets, but the fungus can be treated through multiple methods. If you think your pet may be infected with ringworm, have your veterinarian examine him/her since several other skin diseases can mimic ringworm.

Pet Talk is a service of the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University.