Biochemical studies on geeldikkop and enzootic icterus

Abstract

The haematology, chemical pathology, disturbed biochemistry, general enzymology and histopathology of geeldikkop, enzootic icterus and icterogenin intoxication in sheep are presented in full for the first time. The relationship of geeldikkop to enzootic icterus is demonstrated and both diseases are shown to be the result of sudden catastrophic failures of membrane permeability in various tissues of the body. The conditions are thought to be two different manifestations of a single disease entity, possibly low grade selenium intoxication. The acute manifestations are precipitated by various forms of non-specific stress the effects of which, on sheep from the areas where the diseases are enzootic, are described. One of the most important factors in this regard is thought to be a virus infection similar in nature to bluetongue. The chemical pathology and haematology of mild bluetongue infections in sheep are thus described in detail. The chemical nature of the ovine bile pigments is described and methods are given for their isolation and identification, as well as for the isolation of bromsulphalein conjugates formed by the ovine liver. Methods are given for the determination of copper in body fluids and tissues, the various copper fractions in blood, and iron and selenium in body tissues. The diagnosis of ovine liver, renal and adrenal dysfunction and myopathy by means of clinical laboratory tests is fully dealt with. Intermediary metabolism in the ovine red cell is discussed and activity levels of numerous metabolic enzymes in these cells are presented for consideration. Carbohydrate metabolism in the sheep as it is revealed by a study of the disturbances seen in geeldikkop forms an important theme of this thesis.