Generalised demodicosis in a Friesian heifer from a zero-grazing unit.

A Friesian heifer with generalised skin lesions was slaughtered after unsuccessful treatment. It had thickened skin with lumps and nodules, with the severely affected parts thrown into folds over the eyelids, ears, most of the head, neck, legs and perineal area. The affected skin was soft and squamous in appearance. On postmortem examination, all the skin layers were affected and were 10-22 mm thick. There was also lymphadenopathy. Histological examination showed the presence of dermatitis characterised by follicular inflammation. Multiple follicular cysts with keratin squames and numerous demodectic mites were seen. Some mites had migrated to the peripheral lymph nodes causing eosinophilic lymphadenitis and panniculitis of the subcutis.