Catecholamines in dogs during cold adaptation by repeated immersions

Area of Science:

• Physiology
• Environmental Medicine
• Animal Science

Background:

• Cold exposure triggers significant physiological responses in mammals.
• Adaptation to cold environments is crucial for survival and involves complex thermoregulatory mechanisms.

Purpose of the Study:

• To investigate the physiological adaptations of dogs to chronic cold water immersion.
• To determine the effects of cold exposure on thermogenesis and metabolic responses.

Main Methods:

• Dogs underwent daily 1-hour cold water immersions for 30 consecutive days.
• Physiological parameters including oxygen uptake, colonic temperature, and plasma concentrations of epinephrine, norepinephrine, glucose, lactic acid, and free fatty acids were measured.

Main Results:

• Initial immersion caused a sevenfold increase in oxygen uptake and decreased colonic temperature, with elevated plasma stress hormones and metabolites.
• By the 10th immersion, oxygen uptake further increased, colonic temperature drop lessened, and plasma epinephrine, glucose, and lactic acid decreased, while free fatty acids remained elevated.
• After 30 days, no enhanced calorigenic response to epinephrine or norepinephrine infusion was observed, suggesting alternative adaptation mechanisms.

Conclusions:

• Ten hours of cold exposure are sufficient to induce an improved capacity for heat production in dogs.
• Cold adaptation in dogs may involve mechanisms beyond enhanced sensitivity to catecholamines like norepinephrine.
• Further research is needed to elucidate the specific pathways involved in nonshivering thermogenesis during prolonged cold adaptation.