Thermal Imaging to Assess the Health Status in Wildlife Animals under Human Care: Limitations and Perspectives

Ensuring the welfare of wildlife under human care requires tools to monitor their health and well-being. Infrared thermography is a non-invasive technique for assessing thermal states that measure the radiation emitted from the skin in distinct anatomical areas, known as thermal windows—anatomical regions with abundant capillaries and arteriovenous anastomosis that facilitate heat exchange with the environment. However, thermal windows for wildlife species have not yet been established due to the different characteristics of their skin, coats, fur, or coloring. This review discusses published information on the usefulness of the ocular, nasal, thoracic, abdominal, and podal anatomical regions as thermal windows for evaluating these animals’ thermal responses and health status and monitoring habitat design. Another aspect that must be considered for wildlife under human care is the limitations of distinct species due to differences between animals and critical factors. Future studies should focus on establishing a precise application for each thermal window according to the specific characteristics of distinct animal species

Effect of solar radiation on thermoregulatory responses of Santa Inês sheep and their crosses with wool and hair Dorper sheep

This study aimed to assess the thermoregulatory responses of Santa Inês (SI), Dorper x Santa Inês (CH) and White Dorper x Santa Inês sheep (CW) to direct solar radiation in Southeast Brazil. Thirty adult non-pregnant and non-lactating Santa Inês (SI) hair ewes and their crosses with Dorper (hair ewes) and White Dorper (wool ewes) were allocated into three groups n = 10 and exposed to continuous solar radiation for three consecutive days. Ocular and surface temperatures, measured by infrared thermography, the rectal temperature, respiratory rate and sweating rate were collected at 7:00, 13:00 and 20:00 h. During the experiment, the black globe temperature reached a peak at 13:00 h, reaching mean values of 43.5 °C ± 0.45 °C, representative of severe discomfort for sheep. All genotypes showed an increase in surface temperature, reaching the maximum value at 13:00 h. The wool White Dorper x Santa Inês showed significantly higher surface temperature (dorsal, ventral, and shoulder) than the other genotypes. All the genotypes showed similar rectal temperature increases, peaking at 13:00 h, with values close to 39.4 °C ± 0.12 °C. At 20:00 h, all the genotypes decreased the rectal temperature (RT), albeit not reverting to the 7:00 h values. Changes in ocular temperature values mirrored the RT. All the genotypes presented high levels of evaporative heat loss. Even though all breeds significantly increased the respiratory rate, Santa Inês exhibited significantly higher values (146 bpm) than the others (112 and 117 for CH and CW, respectively). The sweating rate was very high in all genotypes, without differences among them, and exhibiting the same trend with a maximum value at 20:00 h. This behavior reflects the continuous effort to lose heat during the day, despite the decrease in black globe temperature. This study revealed analogous thermoregulatory responses among genotypes groups studied. The three genotypes showed similar heat tolerances, albeit presenting different thermogenesis and thermolysis dynamics, as evidenced by the maintenance of rectal temperatures within physiological limits even when subjected to intense high solar radiation