Thermolability, Heat Tolerance and Renal Function In the Dassie or Hyrax, Procavia Capensis

Abstract

In a series of experiments, designed to examine renal function and thermoregulation in the dassie, the following observations were made: The dassie is unable to exist indefinitely on a dry diet without water. After 8 days without water, feed intake ceases. Water consumption is relatively low, amounting to 45,7 mllkg, which suggests efficient renal function. Faecal water loss is minimal wh.en the animals are dehydrated. A faecal moisture value as low as 35 per cent was obtained after nine days of dehydration. The capacity of the dassie kidney to concentrate electrolytes and urea is very high. The maximum recorded osmolality of the urine was 3 088 mOsm/kg, which is comparable to that of the camel. The most unusual feature of renal function in the dassie is the excretion of large amounts of undissolved calcium carbonate in the urine. The body temperature at comfortable ambient temperatures (2OC) was lower than expected for a mammal of this size and may be implicated in spermatogenesis in the intra-abdominally situated testes of these animals. The dassie appears to be very thermolabile and has surprisingly low heat tolerance. Above 35C (ambient) the animals develop hyperthermia and exhibit fairly profuse nasal sweating. The upper incipient lethal temperature appears to be above 35C but less than 4OC.