Infrared Thermal Imaging and Blood and Faecal Cortisol Measurements for Stress Assessment in Rabbits During Blood Sampling.

Background: This study evaluated physiological responses to repeated handling and blood collection in laboratory rabbits using infrared thermography, serum cortisol, and faecal cortisol metabolites (FCMs), and assessed responses in non-handled rabbits housed in the same room. Methods: Sixteen healthy adult rabbits were randomly allocated to experimental (n = 8) and non-handled control (n = 8) groups. Experimental rabbits underwent nine blood collections over 5 h as part of a pharmacokinetic study, with periocular surface temperature measured by infrared thermography before each collection. Controls underwent thermography at identical time points without handling or blood sampling. Serum cortisol was measured in experimental rabbits, whereas FCMs were analysed in both groups. Results: Following the first blood collection, periocular temperature increased by 1.0 °C in experimental and 1.3 °C in control rabbits. Experimental serum cortisol increased from 13.6 ± 5.5 to 23.7 ± 7.3 ng/mL at 30 min and declined to 8.1 ± 2.1 ng/mL at final sampling. FCMs increased approximately 9 h after the first collection in both groups and remained elevated for up to three days in experimental rabbits. Conclusions: Repeated handling and blood collection elicited measurable physiological responses. Changes in controls suggest that procedure-related environmental cues may also influence nearby non-handled rabbits.