The Study of Sheep With Permanent Unilateral Parotid Fistulæ

Abstract

1. A new technique has been developed for the preparation of a permanent parotid fistula in the sheep. The advantage over the Pavlov‐Glinski operation is that the saliva drips from the dependent point of a skin teat. The secretion rate may be unobtrusively observed without fixation of any apparatus to the animal. Thirty‐seven sheep with parotid fistulæ have been studied. 2. The presence of a parotid fistula for 6–93 weeks did not involve any anatomical or histological deviation from normal in the parotid gland. 3. A sheep with a parotid fistula lost each day 1–4 l. of hypertonic alkaline saliva containing 160–650 m.equiv. of Na+. The animal could be maintained in good condition indefinitely provided enough Na+ was given to replace that lost from the fistula. Digestion proceeded normally. 4. The rate of parotid salivary secretion increased during eating and rumination, and decreased during starvation or water depletion. 5. The response of the animal to Na+ depletion was examined under strictly controlled conditions. The sheep has remarkable parotid and renal mechanisms of electrolyte regulation. The salivary Na+ concentration falls commensurately with Na+ depletion from a normal of 180 m.equiv/l. to as low as 10 m.equiv/l., and the salivary K+ concentration rises equivalently from 10 m.equiv/l. to 180 m.equiv/l. This allowed the sheep to establish a new Na+ equilibrium at a particular level of Na+ depletion. It could survive for weeks even though depleted of several hundred m.equiv. of Na+. Because of the nature of the fluid dynamics of digestion in the ruminant, the mechanism of conservation of salivary Na+ during Na+ depletion may have survival value under stringent environmental conditions such as drought. 6. A sheep with a parotid fistula licked 5–15 g./day off a salt block which was provided in its cage. Prior to operation a normal sheep usually licked off only 0·5–2 g./day.

Muzzle Secretion Electrolytes as a Possible Indicator of Sodium Status in Buffalo (Bubalus bubalis) Calves: Effects of Sodium Depletion and Aldosterone Administration

“…Although the reciprocal changes in the cationic composition of saliva during sodium depletion have been reported in other ruminant species by several investigators (Denton 1957;Dobson 1963;Whipp et al 1966 andRai et al 1973) the existence of such a relationship in the muzzle secretion of sodium~depleted buffalo calves is an interesting observation ofthe present investigation. A function of the muzzle gland is to keep the muzzle area moist, a moist muzzle being a sign of health (Singh and Moore 1978).…”

The Pressor Effect of Angiotensin Ii in Pregnant Sheep

“…Six experiments were performed on 3 ewes with parotid fistulae when they were made approx. 400 niEq Na deplete by having their sodium supplement withdrawn for 2 days (Denton, 1957). Control experiments were done on 3 non-pregnant ewes.…”

“…A unilateral parotid Estula was made in 3 of these animals (Denton, 1957). Stage of gestation was assessed retrospectively when the animals were later sacrificed, and size and maturity of the foetuses recorded.…”

Sodium Dynamics in a Northern Ecosystem

“…It may be accomplished by ion shifts within the rumen-saliva system or by storage and withdrawal in bone. Preliminary data of the dicate that these moose probably substitute potassium for sodium in parotid secretion, a response found in sheep during sodium deprivation (28).…”