Equine Bacterial and Fungal Diseases: A Diagnostic and Therapeutic Update

Bacterial and fungal skin diseases are important in the horse. Bacterial skin diseases (pyoderma) are most often caused by Staphylococcus species, Corynebacterium pseudotuberculosis or Dermatophilus congolensis. The most common clinical signs associated with bacterial skin infections are crusts, papules, abscesses, and draining tracts; the latter two lesions are more commonly associated with C. pseudotuberculosis. Ideally, antibiotic treatment should be based on bacterial culture and sensitivity. Fungal infections are most commonly caused by dermatophytes (“ringworm”) or Sporothrix schenkii, although the role of Malassezia in equine skin disease is beginning to be investigated. The clinical signs of fungal infections are variable and may include alopecia, crusts, papules, pruritus, nodules, ulcers, and draining tracts. The latter three lesions are more commonly associated with S. schenkii infection. Treatment is dependent on the organism cultured and may include both topical and/or systemic treatment.