Although fungal disease is uncommon in rodents, dermatophytosis is the most common mycosis seen in clinical practice. T. mentagrophytes is the most common etiologic agent, and the guinea pig is the most common species affected, although there are reports in all pet and laboratory rodent species except the gerbil. Despite the low incidence of clinical disease, rodents are common asymptomatic carriers of dermatophytes, and ringworm is the most common zoonotic disease transmitted from rodents to people.