Quantifying Body Surface Temperature Differences in Canine Coat Types Using Infrared Thermography

Abstract: Infrared thermography (IRT) has been used to assess the health of canines by measuring surface temperatures. However, little is known about the effect hair coat differences has on expected surface temperature in healthy canines under the influence of hair coat differences. The aim of this study was to identify the influence of coat characteristics in body surface temperature (BST) in canines (Canis lupus familiaris).

To determine the changes in BST, an infrared thermal imaging camera (i.e. FLIR B400) was used. Thermal images of the left and right sides of privately-owned dogs (n = 50) were acquired. Each animal acclimated in an indoor environment away from direct sunlight (23 ± 2.0 °C) for 15 min, and images were taken at a distance 0.67 ± 0.24 m. Regions of interest (ROIs) of mean surface temperatures were examined across the lateral surface of each animal.

No statistical differences were detected based on laterality (P = 0.08). Mean BSTs were categorized by each dog's hair coat type: short coat (SC), curly coat (CC), long coat (LC), and double coat (DC). These BSTs were then analyzed using two-way analysis of variance, or ANOVA, (Shapiro-Wilk) and pairwise comparison. SC animals had the highest BST (31.77 ± 0.19 °C; P < 0.001) whereas LC (28.14 ± 0.31 °C; P < 0.001) and DC animals (28.25 ± 0.23 °C; P < 0.001) were lower in BST. CC animals portrayed intermediate BST (29.85 ± 0.33 °C; P < 0.001).

The Pearson correlation and one-way ANOVA between rectal temperature and BST and coat type were not statistically significant (r = -0.24 and P = 0.07, respectively). Results indicate that short-haired dogs exhibit a more drastic increase in BST (approximately 2 °C) in comparison to other dogs and this should be considered in future clinical applications.

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Reference: Claire J Kwon , Cord M Brundage (2019) J Therm Biol May;82:18-22.