Ringworm shows no green glow under a Wood’s lamp, scaling is nearly gone, but it’s still red and fur still comes out in clumps when pulled — what now?

Not every fungal infection glows green under a Wood’s lamp; its accuracy is under 60% and it only detects Microsporum (small-spore) fungi, so while it is a useful clue it is not 100% diagnostic.

If symptoms are not controlled after medication, take the cat to the vet for a skin scraping or a fungal culture of the affected hairs to identify the exact skin disease before treating. No green fluorescence may mean it is a non-Microsporum fungus, or the fungus improved with long-term use but a secondary mixed skin infection developed — get a scraping done. Typical ringworm signs are hair loss, red skin, rash, itch, and scattered dandruff; severe cases can ulcerate.