Diuresis due to stress in cattle.

Abstract

IN the course of investigation of some aspects of renal function in adult dairy cattle, it was noted that there was a marked diuretic response to a painful stimulus. The animals used were non-lactating, non-pregnant Ayrshire dairy cows accustomed to experimental procedures, and the stimulus was puncture of the brachial artery by the technique described by Fisher1, which, despite the use of local anaesthetic, always caused some discomfort. Arterial puncture was carried out during continuous urine collection by an indwelling urethral catheter for renal clearance measurements. In association with the increased rate of flow after arterial puncture, urine became noticeably paler in colour, and there was a marked fall in urinary bicarbonate concentration. Cystometric measurement of bladder pressure showed that there was no variation in intracystic pressure at the onset of diuresis, and, on the basis of these observations, it was assumed that the increase in the rate of urine collection was a true reflexion of increased rate of formation, rather than the expulsion of uncollected urine from the bladder.