Use of Infrared Thermography to Detect Thermographic Changes in Mule Deer (<i>Odocoileus hemionus</i>) Experimentally Infected with Foot-and-Mouth Disease

Infrared thermography (IRT) measures the heat emitted from a surface, displays that information as a pictorial representation called a thermogram, and is capable of being a remote, noninvasive technology that provides information on the health of an animal. Foot-and-mouth disease (FMD) caused by FMD virus (FMDV) is a severe, highly communicable viral disease of cloven-hoofed animals, including both domestic and wild ruminants. Early detection of the disease may reduce economic loss and loss of susceptible wildlife. The objective of this study was to evaluate the use of IRT to detect possible heat changes associated with sites of infection with FMDV in experimentally infected mule deer (Odocoileus hemionus). Infection occurred through either inoculation with FMDV or exposure to inoculated animals. Early vesicular lesions were observed on the mouth, feet, or both within 24 hrs postinoculation and 48–96 hrs post-exposure. From internal temperature sensors, the exposed animals’ body temperatures elevated significantly from the pre-infection temperature (38.8uC, P # 0.002) starting the day before any lesions were observed. Body temperature was also found not to be significantly different from eye temperatures of well-focused thermograms. For feet thermograms, the mean of the daily maximum (MMAX) foot temperature rose significantly (P 5 0.017) from two days before (27.3uC 6 1.9uC SE) to the maximum MMAX observed (33.0uC 6 2.0uC SE) at two days after the first foot lesion occurrence. These observed changes indicate that IRT may be a rapid, remote, and noninvasive method to screen for suspect animals in order to test further for FMDV infection during an FMD outbreak.