Do I Need to Isolate My Dog With Ringworm?

The hairless patches on this pup are classic signs of ringworm infection.
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If your veterinarian diagnoses your dog's skin issue as ringworm, you should try to isolate your dog from other animals -- and people -- in your home. This fungal infection, which isn't a worm, is quite contagious. Formally known as dermatophytosis, ringworm usually affects puppies or older dogs who are in poor condition. If it's too late or virtually impossible to isolate your dog, don't despair. Ringworm is a nuisance, but it's not life-threatening.

Canine Ringworm

Dermatophytosis infections receive the name ringworm because the lesions form a ring on the skin. If your dog loses hair, and circular lesions appear in the area, it's likely he's come down with ringworm. While three types of fungi can cause dermatophytosis in canines, Microsporum canis is the culprit in more than 70 percent of cases. Transmission results from contact between an infected dog or person and a noninfected dog or person. A human adult's immune system usually resists the infection, but that's not necessarily true with kids.

Ringworm Diagnosis and Treatment

Your vet diagnoses ringworm by examining affected hairs under a microscope or special fluorescent light. Using these methods, she can see ringworm spores. She might also culture a hair sample for a definite diagnosis. Ringworm is self-limiting -- it will eventually go away on its own after a few weeks or months. That doesn't mean you shouldn't treat it. Treatment lessens the length of the infestation and helps stop its spread. Your vet might prescribe a combination of special shampoos or dips, oral anti-fungal medication or topical treatment, and may shave hair from affected areas. Treatment can last for six weeks or more and stops when your dog receives a second consecutive ringworm negative culture.

Ringworm Isolation

While it's a good idea to isolate a dog with active ringworm, the incubation period lasts between 10 and 12 days before symptoms become evident, so it's likely he's already spread the fungi. If he does have ringworm, don't take him to the dog park, to doggie daycare or on any outings where he is certain to run into other dogs. If you have more than one dog in your home, or cats, the other pets have probably been exposed, but they might never become symptomatic. However, take them to the vet for testing and treatment. Keep infected animals in an area that's easy to clean and disinfect. Keep human visitors to a minimum, and keep your animals away from them.

Treating the Environment

Ringworm spores can stay in the pet's environment for months. That means you must disinfect or discard many of your dog's belongings, including his food and water bowls, toys and brushes. Wash all of the pet bedding in hot water with bleach in the washing machine, or throw out the old bedding and purchase new items. You can kill spores on carpets or furniture with a solution of 1 pint of bleach per 1 gallon of water, if such treatment won't affect the items.