Observations on disease-associated preferred body temperatures in reptiles

Abstract

Reptiles have been reported to voluntarily maintain higher optimum body temperatures when discase is present. This behavioural strategy raises the metabolic rate, and presumably also the effectiveness of the immune system. Based largely upon this concept, keepers of reptiles often raise environmental temperatures to assist the recovery process. Case studies of disease in reptiles held privately and in other collections over a 12-year period implied that while behaviourally thermoregulated, and imposed, warmer temperatures appeared often to assist recovery, in other cases imposed warmer temperatures accelerated the disease, resulting in rapid deterioration or fatalities. A common feature observed among captive reptiles in early stages of disease was that higher preferred body temperatures were behaviourally sought, while in more advanced and serious cases, lower preferred body temperatures (leading in certain cases to torpor) were behaviourally sought. This communication examines some aspects of the aetiology of disease-associated preferred body temperatures, and suggests that behavioural thermoregulation of body temperature during disease is far more complex than was previously assumed. It is hypothesized that while a warmer temperature may offer an immunological stimulant as previously thought, and as such is often totally appropriate, stress from the disease itself (potentially complicated and increased by environmentally induced stress or distress) may act as an immunological suppressant, and thus recovery requires a “biological shut-down”, as achieved during cooler temperatures. Lower and minimum body temperatures, however, are not suggested here as forming routine recovery enhancement or treatment, rather that observed behaviours during disease, and apparent enhanced recovery, suggest that lower preferred body temperatures may be integral to healing under certain conditions, and in this regard encouragement might be appropriate. The process appears difficult to define and may incorporate strategies of dual, multiple, or alternating sequential behavioural thermoregulation or imposed body temperature variation in the healing process. The potential for, in particular, captive animal treatment is also discussed.