Infrared Thermography as a Diagnostic Tool for Pododermatitis in Captive Greater Flamingos (Phoenicopterus roseus)

Abstract

This cross-sectional study investigated the use of infrared thermography as a diagnostic tool for pododermatitis in captive greater flamingos (Phoenicopterus roseus). Photographs and thermal images were obtained for 775 feet from 408 flamingos held at three UK zoological collections. The feet were divided into eight regions, which were assigned a score for hyperkeratosis, fissures, nodules and papillomatous growths according to a previously defined scoring system. Minimum, mean and maximum temperatures were recorded for each region. 97 feet (12.5%) were scored as normal (no lesions or only mild hyperkeratosis), whilst 678 (87.5%) were scored as abnormal. It was found that 99.9% (95% confidence interval (CI): 99.3–100%) of the scored feet exhibited hyperkeratosis, 61.7% (95% CI: 58.2–65.1%) fissures, 16.0% (95% CI: 13.5–18.8%) nodules and 38.5% (95% CI: 35.0–42.0%) papillomatous growths. Thermal data assessed using general linear mixed effect modelling showed that regional and individual bird temperature differences accounted for most of the temperature variation, but there was a statistically significant (P<0.05) difference between regions with nodules versus regions without when using maximum temperatures. Intra- and inter-foot variation, using a regional correction factor and ankle temperatures, was assessed for 272 birds, where temperature distributions for each lesion type were compared with that of normal regions using t-tests. A statistically significant difference (P<0.05) was found between corrected values for regions with hyperkeratosis and papillomatous growths compared with normal, but no difference was found for fissures or nodules. Despite the differences found, the results suggest that infrared thermography may not be a practical diagnostic tool for pododermatitis in flamingos due to wide temperature variations between and within normal feet and a great degree of overlap of temperatures between normal and abnormal feet.