Ringworm

Ringworm is not a worm at all but a fungus (dermatophyte) that is found in the environment. It will attach to the skin of dogs or cats and may or may not cause disease. Some animals carry the fungus on their skin and
never show signs of skin disease. Other pets will develop severe skin disease from exposure.

In dogs, Microsporum or Trichophyton are usually the causative agents when a patient is diagnosed with ringworm. In cats, it is usually Microsporum. As noted above, some animals show no symptoms. In other cases, circular hair loss with mild crusting and scaling is the classic sign. Most animals are minimally itchy and hair loss is the most noticeable sign.

Treatment can be extremely frustrating and time-consuming. This fungus is quite contagious to animals and humans so multiple pets may need to be treated. The environment (bedding, floors) should be addressed and
treated with diluted bleach if possible. In very mild cases, topical therapy can be initiated, especially when waiting for the ringworm culture results. Shampoos or lotions with miconazole can be applied. Lime-sulfur dips can be performed, but are very malodorous and must be done in hospital.

Oral anti-fungals such as griseofulvin or itraconazole are indicated if the culture is positive or the patient has many ringworm lesions. These medications need to be given for a minimum of 6 weeks and may need to
be given for many months. The patient needs to be monitored closely for side effects (vomiting, diarrhea, liver toxicity) due to the length of time these medications are given.

Remember this fungus can be contracted by humans, especially children on immune compromised adults.