Mechanisms of cold acclimatization in the cat

¹ Environmental Physiology Branch, Civil Aeromedical Research Institute, Federal Aviation Agency, Oklahoma City, Oklahoma

Thermoregulatory control in cats living at 25 C was compared to the regulation of body temperature in the same species after continuous whole-body cold exposure to an ambient temperature of 5 C for periods exceeding 2 months. Rectal and extremity temperatures and metabolic rates for the two groups were examined during acute (2-hr) air exposures to 23, 10, and 0 C. Cold acclimatizing mechanisms in the cat involve a redistribution of body heat at 23 C, obligating increased heat flux at the expense of elevated metabolism, an improved peripheral vascular defense (increase functional tissue insulation) during moderate cold exposure (10 C), and a greater ability to increase heat production accompanied by more labile peripheral vasomotion, during more severe cold air exposure (0 C). Although resting at 23 C, cold-acclimatized cats had lower rectal temperatures and were able to maintain higher internal body temperatures during both levels of cold stress compared to noncold-acclimatized animals.