Ringworm on Cats

Can I use tea tree oil on my cats for ringworm?

Ringworm is not actually caused by a worm; it's caused by a fungus. Itching and hair loss are the most common symptoms, and it can be transmitted to humans. Typically, a veterinarian would treat the cat with external and internal drugs over a period of time to cure the infection.
Tea tree oil is a very effective fungicide when applied to infected skin in humans. I have used it with great success against ringworm. But according to veterinarian Susan Wynn, tea tree oil is extremely toxic to cats. She says that it has to do with "some unique metabolic deficiencies in kitty livers."