Physiological responses of dogs on exposure to hot, arid conditions. Serum constituents.

Serum electrolytes, metabolites and enzymes were determined in arterial blood of chronically cannulated dogs at room temperature and on exposure to 44-50 degrees C. These dogs were naturally acclimated to hot, arid conditions. In dogs maintaining their rectal temperatures (TR) below 40 degrees C, no significant changes were seen in the levels of Na+, Cl-, cholesterol, uric acid, alkaline phosphatase, lactic dehydrogenase or glutamic-pyruvic transaminase (SGPT). K+, CO2, glucose decreased significantly, and urea nitrogen (BUN) and glutamic-oxaloacetic transaminase (SGOT) showed small but significant increases. In several cases of excitable dogs, in which TR increased above 40 degrees C, we found large, significant increases in uric acid, SGPT and SGOT, and a decrease in cholesterol. The results suggest that in dogs maintaining their TR when exposed to high temperatures, changes in serum constituents indicate merely the presence of respiratory alkalosis and an increased energetic demand. When control of TR is lost, changes occur which suggest liver, and possibly cardiac, tissue damage.