Ovine and Caprine Dermatophytosis Study Guide

Overview and Clinical Importance

Dermatophytosis (commonly called ringworm) is a superficial fungal infection affecting keratinized structures including the stratum corneum, hair shafts, and wool fibers. In small ruminants, this zoonotic disease is particularly important in show lambs (termed club lamb fungus) and is otherwise uncommon in commercial production flocks. Understanding dermatophytosis is essential for the NAVLE because it involves recognizing characteristic clinical presentations, understanding diagnostic approaches, and implementing appropriate treatment while considering zoonotic implications.

Etiology

Dermatophytes are keratinophilic fungi belonging to the Arthrodermataceae family. The primary genera affecting animals are Trichophyton and Microsporum. These organisms produce keratinases that allow them to invade and digest keratin in hair, wool, and the superficial epidermis.

Causative Organisms in Small Ruminants

Epidemiology and Risk Factors

Transmission

Dermatophytes spread through direct contact with infected animals or indirect contact via contaminated fomites. Fungal spores (arthroconidia) remain viable in the environment for years under natural conditions, making environmental decontamination critical.