This observational retrospective study aimed to determine how frequently Microsporum canis was isolated from untreated cats with suspected skin lesions or cats being treated for dermatophytosis after 1, 2, and 3 weeks of incubation on dermatophyte culture mediums. Of 13 772 fungal cultures, 20.9% were positive for M canis. Samples tested positive within 14 days of culture in 98.2% of untreated cats and 96.8% of treated cats. Samples requiring more than 14 days of culture demonstrated abnormal gross morphology. The authors concluded that culture results for M canis may be finalized after 14 days with no growth as compared with the current standard of 21 days. This shortened culture period may improve patient quality of life and decrease costs by minimizing the isolation period for cats with suspected infection.