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ARS Home » Midwest Area » West Lafayette, Indiana » Livestock Behavior Research » Research » Publications at this Location » Publication #313859

Title: Comparing the effects of rapid and gradual cooling on body temperature and inflammatory response following acute hyperthermia

item JOHNSON, J. - Purdue University
item SAPKOTA, A. - Purdue University
item Lay Jr, Donald

Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 1/30/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Hyperthermia negatively impacts human and animal health, and extreme cases can result in mortality if recovery is not appropriately managed. The study objective was to determine the effects of rapid versus gradual cooling on body temperature and the inflammatory response following exposure to acute heat stress (HS) in a pig model. Male pigs (88.7 ± 1.6 kg BW) were exposed to thermoneutral conditions (TN; n = 12; 19.5 ± 0.1°C) for 6 hrs, or HS (36.4 ± 0.1°C) for 3 hrs, followed by a 3 hr recovery period of either rapid cooling (HSRC; n = 12; immediate TN exposure and ice water dousing) or gradual cooling (HSGC; n = 12; gradual decrease to TN temperature). Rectal (TR) and gastrointestinal tract temperatures (TGI) were obtained every 15 min. Blood samples were collected from 6 pigs per treatment group at 60, 180, 210 and 240 minutes and analyzed for TNFa and IL-1ß concentrations. TR was increased (p < 0.01) in HSRC and HSGC pigs compared to TN controls during both HS (1.2°C) and recovery (0.6°C), and was reduced (p < 0.01; 0.4°C) in HSRC compared to HSGC pigs during the recovery period. TGI was increased (p < 0.01) in HSRC and HSGC compared to TN pigs during HS (1.6°C and 1.5°C, respectively) and recovery (1.2°C and 1.3°C, respectively), but was similar (40.8°C) for HSRC and HSGC pigs during both periods. During HS, HSRC and HSGC pigs had increased TNFa concentrations (p < 0.04; 27.5%), but IL-1ß concentrations were similar (p > 0.60; 10.2 pg/mL) to TN controls. In the recovery period, HSRC pigs tended to have increased TNFa concentrations (p < 0.07; 41.2%) compared to HSGC pigs. In summary, although rapid cooling was more effective than gradual cooling in reducing TR during HS recovery it had no effect on TGI and this may be linked to an increased inflammatory response during recovery.