Staphylococcus hyicus in skin lesions of horses.

Staphylococcus hyicus (subspecies hyicus) was isolated as the only pathogenic organism from two independent cases of dermatitis of the lower parts of the limbs (grease heel) in horses. The organism was recovered together with other pathogenic staphylococci from similar conditions in two other horses of different origins. These conditions were characterised by epidermolysis, alopecia and crust formation. They responded quickly to antibiotic treatment. The organism was also isolated from a long standing case of "summer eczema" which healed without antibiotic treatment, and from a horse with dermatophilosis (streptotrichosis, Dermatophilus congolensis infection). Experimentally, Staph hyicus caused epidermolysis, exudation and inflammation in the superficial layers of the skin.