Chapter 1: Ringworm (Dermatophytosis)

What is Ringworm?

Ringworm, or "dermatophytosis", is a fungal infection affecting the skin, hair and occasionally nails of animals (and people). Three species of ringworm fungus most commonly affect cats and dogs:

• Microsporum canis
• Microsporum gypseum
• Trichophyton mentagrophytes

Who gets Ringworm?

The dermatophyte species that affect cats and dogs can be passed between these two species as well as to humans and other mammals. Factors that increase risk of ringworm:

• Age - Animals of any age are susceptible, but young animals (<1 yr old) and geriatric animals are at the highest risk.
• Species and breed - Cats are at greater risk than dogs. Persian cats and Yorkshire Terriers are at relatively high risk, as are long-haired cats in general.
• Immune status – Animals with conditions that compromise the immune system such as FIV, FeLV, pregnancy/lactation, malnutrition, anti-inflammatory drugs, cancer, or stress are at an increased risk.
• Preexisting Conditions - Animals with pre-existing conditions that compromise grooming (e.g. URI) or skin integrity (e.g. flea allergies, over-grooming, external parasites) are at increased risk.