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.”
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.
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