My Kitten’s Tail Lost Fur, Shows Green Under a Wood’s Lamp, and Has Yellow-Brown Discharge

Based on your description, the green fluorescence on the kitten’s tail under a Wood’s lamp indicates a fungal infection. The yellow-brown secretions at the base of the tail fur are likely crusted discharge caused by the infection and skin damage.

The recommended approach is to clip the fur cleanly from the affected area, clean it, and then apply an antifungal medication – for example, a terbinafine hydrochloride spray or a topical ointment containing itraconazole or ketoconazole. If the infection is severe, an oral antifungal medication may be given under veterinary guidance.