|Cheng, Heng Wei|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2009
Publication Date: 6/1/2009
Citation: Wilcox, C.S., Patterson, J., Cheng, H. 2009. Use of Thermography to Screen for Sub-Clinical Bumblefoot in Poultry. Poultry Science. 88:1176-1180. Interpretive Summary: Foot infection is one of the major health problems in chickens. Early diagnosis of foot infection is essential for preventing its associated economical loss and improving chickens’ well-being. This study was designed to determine if thermography can be used for the identification of sub-clinical foot infection in chickens. Data showed that there was a correlation (+0.87) between the positive thermal images and visual clinical scores for the foot infection; while the correlation was very weak (+0.27) between the thermal images classified as suspects and a positive visual clinical score. The results suggest that thermography is a more sensitive detector of foot infection than visual appraisal. Thermography could be a useful tool for screening avian populations for signs of foot infection, especially, in an early stage of the disease. The data from the present study can be used by farmers in management practices and other scientists when planning or interpreting their studies.
Technical Abstract: Bumblefoot is a chronic inflammation of the plantar metatarsal and or digital pads of the foot (pododermatitis). It is one of the major health problems of birds including chickens and is responsible for significant economic losses in commercial poultry operations. Bumblefoot is affected by both endogenous and exogenous factors, such as age, diet, housing, environment, and bacterial microbiota. Early diagnosis of bumblefoot is essential for preventing economic loss and improving bird well-being. The object of this study was to determine the suitability of thermography for the identification of sub-clinical bumblefoot in chickens. Experiment I was designed to validate thermography as a tool for screening avian populations for bumblefoot. Based on foot-surface temperature and variations in thermal patterns of 150 hens randomly examined, the hens were identified as either suspect, positive or negative for bumblefoot. Fourteen days later, a visual score of clinical, mildly clinical or negative for bumblefoot was assigned, based on gross pathological changes in the hens classified as suspected by the thermography. There was an +0.83 correlation for bumblefoot between thermal images and visual clinical scores (P < 0.01). In the experiment II, hens whose feet were free of lesions, were inoculated in the metacarpal foot-pad with Staphylococcus aureus. Thermal images and visual clinical scores were taken pre-challenge and 1, 2, 3, 4, and 7 days post-challenge. The correlation between thermal images classified as positive and a positive visual clinical score for bumblefoot was +0.87 (P<0.001). However, the correlation between the thermal images classified as suspect and a positive visual score was only +0.27, suggesting that thermography is a more sensitive detector of sub-clinical infection than visual appraisal. The results indicate that thermography may provide a useful tool for screening avian populations for signs of bumblefoot, especially, in an early stage of the disease, which will improve bird recovery from bumblefoot and well-being.