Ringworm Management in Cats: Deep Welfare Guide
Ringworm Overview
Ringworm (dermatophytosis) in cats is caused primarily by Microsporum canis. It is the most common fungal skin infection in cats, particularly kittens and immunocompromised animals. It is zoonotic — transmissible to humans, causing circular itchy skin lesions. In cats, classic lesions are circular areas of alopecia with scaling; however, lesions may be subtle or subclinical (carrier state). Long-haired breeds (Persians) are predisposed to widespread infection and subclinical carriage.
Welfare Impact
Ringworm causes variable welfare impact. Many cats show mild, localised lesions causing minimal discomfort. Extensive infection causes pruritus, secondary bacterial infection, and self-trauma. In immunocompromised cats (FIV/FeLV positive, kittens, systemically ill), generalised infection may develop. The welfare impact of management can exceed that of the disease itself: isolation in shelter environments removes social interaction; prolonged treatment causes repeated stress.
Diagnosis
Wood's lamp (UV fluorescence): M. canis fluoresces apple-green; a positive result guides initial diagnosis but a negative result does not exclude ringworm. Fungal culture: the gold standard, but takes 2-4 weeks. PCR testing: rapid, sensitive detection from coat brushings, used increasingly in shelter settings. Direct microscopy: identifies fungal hyphae on hair shafts. In shelter outbreaks, systematic screening of all cats (toothbrush fungal culture) identifies carriers.
Treatment
Systemic antifungal therapy is required for widespread infection: itraconazole (5mg/kg every other day) is first-line in the UK; terbinafine is an alternative. Topical therapy (enilconazole rinse, miconazole/chlorhexidine shampoo, lime sulphur dip) reduces environmental contamination and speeds resolution. Treatment duration: until 2 negative fungal cultures taken 1 week apart. In shelters, the MAC protocol (consistent topical + systemic treatment, environmental decontamination) reduces outbreak duration.
Environmental Decontamination
Environmental contamination is the primary persistence mechanism in multi-cat environments. Viable fungal spores persist for months in carpets, furnishings, and air conditioning ducts. Decontamination requires: thorough cleaning to remove hair and scale (vacuum, damp wipe); dilute bleach (1:10) or enilconazole spray on hard surfaces; launder bedding at high temperature; HEPA vacuuming; and removing cats from contaminated areas during treatment. Shelter design using easily cleanable materials reduces persistence.