Drinking by dogs during and after running.

Abstract

SUMMARY1. Drinking by dogs has been studied during and after running on a treadmill, and compared with the drinking produced by NaCi given by stomach tube or intravenously.2. When water was offered with a delay of more than 5 min after the end of a run producing loss of 30-90 g water by panting, the drinking was similar to that produced by NaCl, assuming that loss of 100 g water produces the same increase in plasma sodium as 15 m-mole NaCl. It is thus possible to explain drinking with a delay after the run as due to loss of water.3. When water was offered immediately after a run or during pauses in the running there was drinking which cannot be explained as due to loss of water. Although the immediate stimulus to drinking is small, it may cause repeated small drinks by which the evaporative loss of water during running is matched by water intake. 4. Water (10-20 ml./kg body wt.) given by stomach tube before the run reduced or abolished drinking during running. Doses of water sufficient to stop drinking did not cause an increase in urine volume.5. From these results a figure is produced placing in order mechanisms which may contribute to the control of water balance.

Increase in Weight and Water Retention on Overfeeding Dogs

“…O'Connor (1982) has presented the factors which determine drinking and urine volume: in dogs doses of water of 100 ml given by stomach tube inhibit drinking (O'Connor & Potts, 1969;O'Connor, 1975); larger doses of water produce an increased volume of dilute urine (water diuresis). In the double-feeding experiments of this paper, retention of 500 g or more of water neither stopped drinking nor produced water diuresis.…”

Post‐prandial Drinking by Dogs

“…Water deposited in cells or lost in the urine is effectively a deprivation of the rest of the body by this amount of water. Dehydration of 50 g is capable of causing drinking in dogs at rest [O'Connor, 1975], the mechanism presumably being increase in the osmotic pressure or Na concentration of the blood. This seems a likely explanation ofpost-prandial drinking in the dog.…”

“…This form of drinking was reproduced by O'Connor [1975] in experiments in which drinking was studied during the controlled activity of running on a treadmill. O'Connor [1975] concluded that activity immediately caused both panting and drinking so that the water lost by evaporation during panting was promptly replaced and dehydration thus avoided.As well as drinking during activity, O'Connor and Potts [1969] also recorded drinking at night after the daily meal eaten at 17.00 and when the dogs were quiet in their cages. Between 17.00 and 03.00 the dogs often took one or more drinks, usually larger than 50 ml, which formed a variable but considerable contribution to the daily water intake.…”

“…Much of the drinking consisted of small drinks, less than 50 ml, taken at those times during the day when the dogs were active in their cages. This form of drinking was reproduced by O'Connor [1975] in experiments in which drinking was studied during the controlled activity of running on a treadmill. O'Connor [1975] concluded that activity immediately caused both panting and drinking so that the water lost by evaporation during panting was promptly replaced and dehydration thus avoided.…”

The relative importance of thermal, osmotic and hypovolaemic factors in the control of drinking in the pig.

“…Central thermally sensitive elements in the hypothalamus may also have been involved in drinking since Andersson, Gale & Sundsten (1962) found that changing hypothalamic temperature usually affected drinking even in the absence of dehydration in the goat. In the dog, O'Connor (1975O'Connor ( , 1977 has demonstrated that exercise or panting under the influence of radiant heat also produced an increase in drinking even before dehydration. O'Connor suggested that raised skin temperature during radiant heating itself is a direct stimulus to drinking.…”