Submitted to: Mizzou Pork Pages
Publication Type: Other
Publication Acceptance Date: June 18, 1999
Publication Date: N/A
Technical Abstract: Pre-weaning mortality rate for piglets farrowed and weaned on U.S. farms in 1998 averaged 13%. While these losses cannot be attributed to any one factor, infectious disease is a major contributor. Infections elicit a cascade of defensive events referred to as the acute phase response (APR). Fever, a consistent physiological response associated with the APR, is necessary for protection against detrimental effects of immunological insults to the body. In this study, piglets (24 hr old) were placed in either a warm (93.2 deg F) or cold (64.4 deg F) environmental temperature (ET) to evaluate their response to lipopolysaccharide (LPS; mimics a bacterial infection). For piglets exposed to the 93.2 deg F, rectal temperatures (RT) increased for the first 45 min, whereas for piglets exposed to the 64.4 deg F, RT decreased during this period. At 64.4 deg F, LPS treatment caused a dramatic decrease in RT that lasted for 2.5 hr. RT was not affected by LPS treatment in piglets at 93.2 deg F. ET also playe a critical role in the amount of body weight loss during the 3-hr period. Piglets that received LPS at 64.4 deg F lost more body weight compared to any of the other piglets. Cortisol (a stress indicator) was elevated by exposure to 64.4 deg F and by LPS. In a follow-up study, piglets were exposed to a cold (64.4 deg F) ET and their response to LPS with or without pre-treating with indomethacin (a non-steroidal anti-inflammatory similar to aspirin and ibuprofen) was evaluated. Results revealed that indomethacin prevented the LPS-induced sickness and hypothermia in piglets exposed to a cold ET. These studies provide evidence that when combined, but not singly, cold stress and exposure to endotoxin induced a rapid and potentially dangerous loss of body temperature in the piglet.