Reference intervals for eye temperature measured by infrared thermography and rectal temperature in dogs

Abstract Objective. To estimate a reference interval (RI) for eye temperature (ET) in apparently healthy shelter dogs using a robust method suitable for moderate sample sizes, and to provide a comparative reference interval for rectal temperature (RT). Methods. This cross-sectional study analyzed ET measurements from a field dataset collected in a municipal shelter. The study population consisted of 78 apparently healthy dogs. ET was obtained with a handheld thermal camera under standardized procedures. Rectal temperatures were obtained from the same dogs using a digital rectal thermometer. The central 95% RI was estimated using a robust statistical method with bootstrap-derived 90% confidence intervals (CIs) for the limits, an approach recommended for datasets with 40 ≤ n < 120 observations. Results. The estimated 95% RI for ET was 35.0-38.5°C with 90% CIs of 34.7–35.4°C (lower limit) and 38.2–38.8°C (upper limit). The 95% RI for RT was 37.5–39.7°C with 90% CIs of 37.3–37.8°C (lower limit) and 39.5–39.9°C (upper limit). Conclusions. These findings provide RIs for ET and RT in apparently healthy shelter dogs. Values approaching or exceeding these limits may warrant additional clinical evaluation. The intervals may serve as an initial benchmark for temperature assessment in similar populations. Clinical Relevance . Population-based RIs for eye and rectal temperatures of dogs are needed to assist veterinarians and shelter personnel in interpreting ET and RT measurements and identifying dogs that might require further clinical examination. Ocular thermography may offer a practical screening tool for body temperature assessment in shelter settings where rapid, low-stress evaluation is desirable.