Relationship between mean body surface temperature measured by use of infrared thermography and ambient temperature in clinically normal pigs and pigs inoculated with Actinobacillus pleuropneumoniae

Objective-To determine the relationship between ambient temperature and mea n body surface temperature (MBST) measured by use of infrared thermography (IRT) and to evaluate the ability of IRT to detect febrile responses in pig s following inoculation with Actinobacillus pleuropneumoniae. Animals-28 crossbred barrows. Procedures-Pigs (n = 4) were subjected to ambient temperatures ranging from 10 to 32 C in an environmental chamber. Infrared thermographs were obtaine d, and regression analysis was used to determine the relationship between a mbient temperature and MBST. The remaining pigs were assigned to groups In an unbalanced randomized complete block design (6 A pleuropneumoniae-inocul ated febrile pigs [increase in rectal temperature greater than or equal to 1.67 C], 6 A pleuropneumoniae-inoculated nonfebrile pigs [increase in recta l temperature < 1.67 C], and 12 noninoculated pigs). infrared thermographs and rectal temperatures were obtained for the period from 2 hours before to 18 hours after inoculation, and results were analyzed by use of repeated-m easures ANOVA. Results-A significant linear relationship was observed between ambient temp erature and MBST (slope, 0.40 C). For inoculated febrile pigs, a treatment X method interaction was evident for rectal temperature and MBST, whereas i noculated nonfebrile pigs only had increased rectal temperatures, compared with noninoculated pigs. A method X time interaction resulted from the long er interval after inoculation until detection of an increase in MBST by use of IRT. Conclusions and Clinical Relevance-infrared thermography can be adjusted to account for ambient temperature and used to detect changes in MBST and rad iant heat production attributable to a febrile response in pigs.