Ringworm is a fungal infection caused by several types of microsporum and trichophyton fungus. Hair and fur loss in affected areas is common, and the disease is named for the frequently ring-shaped lesions on the skin that form as the infection moves outward in a radial fashion. Pets are common carriers, but many other types of animals also can be infected by ringworm and can transmit it to humans and to other species. Ringworm is very persistent in the environment, even when animals are removed. Treatment typically involves use of a natural or medically synthesized antifungal substance.
Cats and Dogs
Cats and dogs are perhaps the best known animal carriers of ringworm. Many felines that come from shelter environments pick up the fungal infection while housed in close quarters with many other cats, where the fungus is often present continuously in the environment. Kittens and puppies in particular can be highly susceptible to infection due to their developing immune systems. Felines and canines with ringworm typically show bare patches of skin that can be scaly or have scabs. The affected areas may or may not exhibit the ringed pattern.
Horses
As for cats and dogs, ringworm in horses usually appears as small patches where the hair tufts and then falls out, revealing a scaly area of skin underneath. According to the Certified Horsemanship Association (CHA), young horses are at risk even more than older horses, but older horses can be infected as well. The CHA recommends isolating infected animals, clipping hair on and around the infected area and using topical and/or oral fungicide as needed.
Sheep
Fred Hopkins, DVM and Warren Gill, Ph.D. explain in a paper for the Agriculture Extension Service of the University of Tennessee that ringworm was considered uncommon in sheep until recently. By the early 1990s, this was no longer the case. The authors cite the practice of shearing very close to the skin as a causal factor, based on both the removal of protective wool and the skin irritation that can result from close shearing. They state that ringworm is rare in wooled sheep and that transmission is also increased when an infected animal is closely sheared.
Farm Animals
Farm animals such as goats, cattle and pigs can also contract ringworm and transmit it to members of other species. The Indiana State Board of Health reports that animals with ringworm are usually barred from exhibitions due to the high likelihood of transmission to people and other animals. According Hopkins and Gill, all types of domestic animal are susceptible, with 80 percent of cases in people in rural areas resulting from transmission from animals.
Other Animals
Rabbits, rodents, ferrets, guinea pigs and birds are also susceptible to ringworm infection. According to the Department of Occupational Safety & Environmental Health at the University of Michigan, nonhuman primates used for laboratory research can also catch ringworm and transmit it to humans, either directly or through the environment.
