Interrelationships among Plasma 17-Hydroxycorticosteroid Levels, Plasma Protein-Bound Iodine Levels, and Ketosis in Dairy Cattle

Plasma levels of 17-hydroxycorticosteroids indicated adrenal-cortical activity and levels of plasma protein-bound iodine indicated thyroid activity in normal and ketotic cows.The 17-hydroxycorticosteroids averaged 5.09 ~g.% for normal and 7.48 ~g.% for ketotic cows, whereas the corresponding protein-bound iodine values were 4.22 ~g. and 2.58 ~g.%, respectively.These results suggest that ketosis might be caused by a relative adrenalcortical deficiency induced by hypothyroidism.Editor.Recent studies on ketosis in dairy cattle, as reviewed by Shaw (22) and by Armour Veterinary Laboratories (1), give substantial support to the concept of ketosis as an endocrine disturbance.Hutyra and Marek (7) in 1926 postulated that adrenal-cortical exhaustion might be involved in ketosis in dairy cows.In 1947, Shaw (21) reported that extracts of the adrenal cortex were effective in treating ketosis.Reports (12,23,26) since then have affirmed the effectiveness of glucocorticoids and ACTtt in treating ketosis.In a series of reports, Shaw and coworkers (5,24,25,27) have presented results of a histopathologic study on 14 ketosis cows.The adrenals of these animals were enlarged, flabby, and showed degeneration of the cortex.Other conditions noted were regressive changes in the anterior pituitary gland, acute involution of the pancreas, involution of the thymolymphatic system, ulcers, nephrosis, and fatty changes in the liver.Fasting animals exhibited some of these same changes (27), but did not show the adrenal and anterior pituitary gland changes.The authors suggested that these tissue changes were similar to the changes which Selye (20) reported as taking place during the alarm-reaction phase of the general adaptation syndrome, and led Hatziolos and Shaw (5) and Shaw et al. (24) to propose that bovine ketosis is due to an adrenal-cortical insufficiency, with possible anterior pituitary gland involvement.