Ringworm is a common fungal infection of hair, skin and nails. In cats, Microsporum canis is the fungus causing approximately >90% of ringworm cases, and can also infect humans. Ringworm is rapidly spread in shelters, persistent in the environment, difficult to control and treat and may be transmitted to caretakers and owners. Fungal culture, the most common test, typically takes a minimum of two weeks to detect a positive result. Newly developed, rapid molecular (PCR) tests are expensive and cannot discriminate between active ringworm infection and residual dead fungal elements. The protocol in many shelters is extended quarantine or euthanasia when M. canis is suspected. These logistically difficult, costly, and distressing measures are entirely unnecessary if the patient is not infected. There is therefore an urgent need for a rapid, cost-effective, sensitive point-of-care diagnostic test to confirm active ringworm infection. This study will therefore assess characteristics of M. canis growth that can be exploited to develop a new rapid diagnostic test. Our preliminary data suggest that a simple chemical reaction can detect M. canis fungal culture with high sensitivity and specificity. Our goal is to further optimize this assay to accurately diagnose ringworm cases directly, and ultimately develop a rapid, accurate test that will be useful in a veterinary clinic or shelter setting. This work holds great promise for significant improvements in ringworm management for individual animals as well as shelter and multi-cat environments.