Xanthosis, an abnormal pigmentation of cattle.

Xanthosis is seen in cattle in the abattoir. It is characterised by a dark brown colour of the heart muscle and certain skeletal muscles such as the masseter because of the presence of lipofuscin pigment. In a survey of its prevalence in 1000 cattle of varying breeds xanthosis was identified in about 25 per cent of Ayrshire cattle and the occasional Ayrshire cross. It was not seen in other breeds. The incidence of one affected and three normal suggests that this condition may result from the inheritance of a simple recessive gene. The relationship of xanthosis to brown atrophy is discussed.