Infrared Thermography for Detection of Bumblefoot (Pododermatitis) in Penguins: Unsuccessful Attempt to Validate as a Diagnostic Test
Bumblefoot (pododermatitis) is an inflammatory or degenerative condition of the foot that causes significant health problems in captive penguins. Penguins with bumblefoot generally develop lesions in the metatarsal pad; early detection is critical to treatment success.2 Captive penguins should be examined regularly for indicators of pododermatitis, including heat, swelling, firmness, or development of lesions. Infrared thermography (IRT) has been utilized to localize areas of inflammation and necrosis by veterinary and human researchers.3 The goal of this study was to validate IRT as a method to diagnose bumblefoot at the subclinical or clinical level. The study group included 60 individuals housed indoors at relatively constant temperature (47–52°F) and humidity (46–51%). Penguins were examined at 3-month intervals. At each exam, bumblefoot lesions were characterized using a previously described scoring system, and a series of thermal images was taken over a 2–3-minute period using a standardized protocol.1 Three different methods were utilized to analyze the thermal images: line, shape, and concentric square. A subgroup of 11 penguins with unilateral lesions was identified so that an affected foot could be compared to a normal foot. Healthy feet were found to have greater surface temperature variability (within the foot) than feet with lesions; however, the variability within an individual over time was such that IRT is not considered a useful tool for detecting pododermatitis in penguins. Furthermore, temperature variability was affected by the length of time the penguin was off the ground, a characteristic that may result from countercurrent blood flow.
I would like to thank the AAZV Zoological Medicine and Wildlife Health Research Grant for funding this research. I would also like to thank the Veterinary, Penguin and Center for Zoo Animal Welfare staffs at the Detroit Zoo for their assistance with this project.
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3. Wilcox CS, J Patterson, HW Cheng. Use of thermography to screen for subclinical bumblefoot in poultry. Poultry Sci. 2009;88:1176–1180.