This chapter discusses the effect of heat stress on the behavioural, physiological, neuroendocrine and molecular responses in chickens. It discusses the range and complexity of molecular, physiological, neuroendocrine and behavioural responses that invoked to maintain body temperatures within the normal range at high ambient temperatures.

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Diurnal rhythm in body temperature of pigeons subjected to different experimental conditions (pinealectomized, sham-operated, melatonin-implanted, cold-exposed) was studied under a 12 h light and 12 h dark regimen. The body temperature of pigeons during photophase was higher than that during scotophase in the normal as well as every treatment group studied. Pinealectomized pigeons showed higher body temperature in the photophase as well as scotophase, than that of the normal and sham-operated birds when examined 2 or 3 weeks following the post-surgical acclimatization to 25 or 3° C. However, subcutaneous implantation of melatonin pellets into pinealectomized pigeons nullified or even reversed the hyperthermic effect of pinealectomy. Exposure of pigeons to – 18° C for 280 min during photophase as well as scotophase, produced a marked drop in body temperature in pinealectomized, sham-operated and normal pigeons. The pinealectomized pigeons exhibited a higher body temperature than that of the sham-operated and normal ones when exposed to –18°C during the photophase, but not during the scotophase. It was concluded that while the pineal is not necessary for maintaining the daily thermal rhythm in the avian body, it has a thermoregulatory role, in that it prevents rise in body temperature in warm (25°C) acclimatized and chronic cold (3°C) exposed birds. In acute short-term cold (-18°C) exposure however, the temperature regulatory role of the pineal was not effective during the scotophase.

The differential diagnosis of hepatic granulomas is vast and includes infections, drugs, immunologic diseases, foreign material exposure, and neoplasia. Silicone, whether directly injected into tissues or used as a filler in breast implants, is known to cause localized granulomatous reactions. It can also migrate to other anatomic locations resulting in granulomatous inflammation at a distance. We report two cases of unsuspected hepatic silicone granulomas in patients undergoing liver biopsy for isolated elevated alkaline phosphatase levels, both with a history of ruptured breast implants. These cases highlight the need for awareness of hepatic silicone granulomas as an etiology of elevated liver enzymes in patients with a history of surgical interventions utilizing silica, such as cosmetic surgery.