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This Article Full Text Full Text (PDF) All Versions of this Article: 294/5/R1666    most recent 00865.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Gray, D. A. Articles by Kamerman, P. R. PubMed PubMed Citation Articles by Gray, D. A. Articles by Kamerman, P. R.

COMPARATIVE AND EVOLUTIONARY PHYSIOLOGY

Restraint increases afebrile body temperature but attenuates fever in Pekin ducks (Anas platyrhynchos)

¹School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; and ²Physiology, School of Biomedical, Biomolecular, and Chemical Sciences, University of Western Australia, Perth, Australia

Submitted 4 December 2007 ; accepted in final form 5 March 2008

In mammals, procedures such as handling, restraint, or exposure to open spaces induces an increase in body temperature (T_b). The increase in temperature shares some characteristics with pyrogen-induced fever and so is often called "stress fever." Birds also respond to acute handling with a stress fever, which may confound thermoregulatory studies that involve animal restraint. We have measured the T_b responses of Pekin ducks on days when they were restrained and compared them to days when the birds remained unrestrained. Restraint induced a 0.5°C increase in T_b that was sustained for the entire 8 h of restraint. To determine whether the restraint-induced increase in T_b is mediated by prostaglandins (PGs) we compared the T_b responses during restraint after intraperitoneal injection with saline to the responses during restraint after injection with diclofenac sodium (15 mg/kg). There was no difference in response, suggesting that restraint affects T_b by a PG-independent mechanism. We also compared the T_b response to intramuscular injection of lipopolysaccharide (LPS; 100 µg/kg), a bacterial pyrogen, when the ducks were restrained or unrestrained. Despite T_b being higher at the time of LPS injection when the ducks were restrained, the maximum temperature reached after LPS injection was higher, and the period that T_b remained elevated was longer when the ducks were unrestrained. We conclude that restraint should be considered as a potential confounder in thermoregulatory studies in birds and presumably other species too.

lipopolysaccharide; psychological stress; birds