Dermatophilosis: It is an acute or chronic, superficial pyoderma caused by the actinomycete, Dermatophilus congolensis. The disease affected a wide range of species in all age groups (cattle, horses, and sheep). NB:
Dermatophilus congolensis -It is a pleomorphic, Gram positive bacterium that grows as filamentous, branching septate mycelium. -It cannot penetrate healthy skin. The two most important predisposing factors in the pathogenesis of dermatophilosis are prolonged wetting and mechanical damage to the skin.
Macro: 1-Raised, roughly circular, thick, laminated, gray-brown scaly crusts on dorsal midline, flank, thoracic wall and shoulders.