Enzootic (Staphylococcal) dermatitis in a Hungarian sheep flock.

Between December 1998 and January 1999 a specific, enzootic dermatitis was observed in a crossbreed sheep flock in Northern Hungary. The affected flock comprised 400 pregnant ewes and 65 (16.2%) of them showed clinical signs during the course of the disease, In the first half of November 1998 these animals grazed on a maize stubble-field, where the left corn-stalks were 35-40 centimetres high. It was likely that these corn-stalks injured the skin of the head. Two weeks later the first clinical signs were observed. Clinico-pathological lesions were usually restricted to one side of the head and particularly affected the skin around the eye, over the nasal and maxillary bones. Skin lesions were erythematous, swollen and irregularly shaped ranging in diameter from 3-8 centimetres. Affected skin surfaces were covered by serofibrinous or serosanguinous exudate (Figure 1). In some cases the odour of the head was foul-smelling. The circumscribed lesions were covered by reddish-brown or brownish-black scabs and were surrounded by a zone of alopecia (Figure 2, 3) In treated ewes the skin lesions persisted for about five weeks and healed without scar formation. After local or parenteral antibiotic treatment the skin lesions healed within two weeks. Histologically the following tissue lesions were found: necrosis and desquamation of superficial layers of the epidermis, ulceration, serofibrinous exudate on the surface of the skin (Figure 4), Subepidermal layers of the skin were infiltrated by mononuclear cells and neutrophil granulocytes, haemorrhages and cluster of Gram-positive bacteria could also be seen (Figure 5). Bacteriological culture from the scabs of six affected ewes yielded coagulase positive Staphylococcus aureus together with coagulase negative staphylococci and streptococci in three cases, while in the other cases arcanobacteria, streptococci and moraxellae grew in mixed culture. The coagulase positive S. aureus strains were identified and characterised by conventional tests (Table) and commercial kits (BBL Crystal, ApiStaph, Staphaurex). Ectoparasites and dermatopathogenic fungi could not be demonstrated. Blood sera of the six affected ewes were negative for the presence of virus antibodies, but were positive for pestivirus (BVD/BD) antibodies. The observed clinical signs and the results of bacteriological culture were very similar Co those reported by SCOTT and others in connection with the "Staphylococcal dermatitis of sheep" (Vet. Rec., 1980. 107. 452-454.) This disease has not been reported earlier in Hungary.