In the fully watered camel thyroid activity is higher in summer than in winter, but activity is reduced in camels deprived of water. The decline in activity is important because the generation of metabolic heat is reduced and respiratory water losses are also reduced. Chronic exposure to heat results in depressed thyroid activity as well as reduced plasma, cortisol and growth hormone concentrations and turnover rates. All three sources normally create heat and act in cooperation, so the net result of habituation to heat is some reduction in metabolic rate (Wilson, 1998). .
