Protect Yourself and your Pets against Ringworm

We all know the joys of sharing our lives and our homes with our pets. Some things, however, are best not shared.

Ringworm, a fungal infection of the hair and skin, is one of a handful of pet infectious diseases that can be transmitted from pets to humans. Guardians often are afflicted along with their pets during an outbreak, and this naturally has generated concern among physicians.

As a pet practitioner, I am very familiar with the challenges of ringworm. In fact, just last week I formulated an extensive treatment protocol for Biggy and Smithy, two tabby cats from the same household, all infected with ringworm. Their guardian had the misfortune of contracting it as well, on her arm.

Depending on their natural habitat, skin fungi can be categorized as geophilic (living in soil), anthrophilic (living on people) or zoophilic (living on animals. Microsporum canis, the species of ringworm that most commonly affects our pets, is a zoophilic fungus that has become so well adapted to pets that it can live on their hair and skin without causing any clinical signs of disease. However, microsporum canis is not part of the flora that normally resides on the skin, and the discovery of this fungus on the skin should always be considered an abnormal finding.

The mere presence of a ringworm spore isn't enough to cause infection and disease. Pets (and humans) must contact a minimum number of spores varies with the individual and the circumstances of exposure. Youth, concurrent disease, drugs that suppress the immune system, compromised immune status, poor nutrition, stress and overcrowding will predispose pets to acquiring ringworm. Pets in animal shelters are much more likely to harbor ringworm then pets at home, and discovery of this fungus on even one pet in a group warrants treatment of the entire animal shelter.

Grooming is one way that pets help to remove ringworm spores from their coats. Long haired pets tend to be less-efficient groomers, making them more inclined to acquire ringworm infections, although genetic influences may play a role in some pet breeds, as well.

Ringworm is an infection of the dead, keratinized portion of the hair and, occasionally, the nails. The fungus uses keratin protein as its nutritional source. It produces enzymes that digest the dead, keratinized tissue, allowing it to penetrate the hair and continue growing. Hair shafts become weak, brittle and easily broken. Hair fragments and skin scales are shed into the environment, along with thousands of spores. Spores can remain in the environment for months or years, serving as a reservoir of infected material for humans and other pets brought into the environment.

The classic clinical appearance of ringworm includes one or more areas of patchy hair loss with mild or moderate crusting. Your pets are most commonly infected, by the head, face, ears and forelimbs primarily involved.

Treatment of ringworm has evolved over the past few years, with new approaches and medications available to veterinarians.