A Hepatogenous Photosensitivity Disease of Cattle: I. Experimental Production and Clinical Aspects of the Disease

Abstract

A hepatogenous photosensitivity disease of cattle caused by feeding of flood damaged alfalfa hay was investigated under experimental conditions. The clinical aspects of the hay-induced disease were characterized and compared with the photosensitization caused by surgically-induced biliary obstruction. The majority of animals which were fed the hay and all those with ligated bile ducts developed photosensitivity which was regularly accompanied by icterus. Lesions of photosensitization were quite variable in degree of severity among individual animals but were essentially identical in both the hay-induced and surgically-induced disease. In all except the severely affected animals skin lesions were confined to those areas not protected by pigment or dense hair coat. Mild lesions developed in some heavily pigmented areas of severely affected animals where the hair was especially short or thin. The climatic conditions under which the alfalfa hay developed toxicity and the similarity of the disease syndrome to that of “facial eczema” in New Zealand suggest that the two diseases may be caused by a hepatotoxin of similar nature and origin.