Thomas, A. D., Orsel, K., Cortés, J. A. et al. 2022. Objective determination and quantification of pain and inflammation associated with digital dermatitis in feedlot cattle. Applied Animal Behaviour Science 253, 105684.

Digital dermatitis (DD) is an infectious skin disease in cattle that causes pain and discomfort, significantly impacting animal welfare. Although DD lesions are painful and prone to bleeding when touched, pain resulting from DD has not yet been objectively quantified. The aim of this study was to objectively quantify pain associated with DD and determine the association between pain and locomotion score (LS). A second objective was to determine the association between foot temperature (FT) and pain. In total 480 cattle (heifers and steers) from 3 feedlots were enrolled. Biweekly pen walks were performed to assess hind feet for DD and altered gait. Cattle presenting with clinical signs of DD during pen walks and at routine re-handling were selected for detailed foot examination. Cattle were assigned an LS [4-point; normal to severely lame) as they walked four strides down an alleyway. Next, while restrained in a chute cattle were clinically appraised for DD, mechanical nociceptive threshold (MNT) measured using pressure algometry, and FT captured using thermal images. Each hind foot was scored as DD absent or present. Further, DD lesions were classified as active or chronic. In total 116 of 510 feet had DD (61 active and 55 chronic) in 255 cattle. Feet with DD lesions withstood 6.37 N less pressure on average than feet without (P < 0.001). Active lesions were most sensitive, withstanding 8.11 N less pressure than feet without (P < 0.001) and 4.06 N less pressure than chronic lesions (P = 0.004). Feet with chronic lesions withstood 4.05 N less pressure than feet without lesions (P = 0.001). Seventy-eight cattle presented with DD of which 34 were lame. Moderate to severely lame cattle withstood 3.1 N less pressure than non-lame cattle (P = 0.01). An increase of 1 oC in maximum foot temperature (MFT) was associated with a 0.60 N decrease in MNT (P < 0.001). Feet with DD had higher MFT compared to feet without (P < 0.001). MFT was higher in active (P = 0.011), and chronic (P = 0.001) lesions compared to feet without lesions. No difference was observed between active and chronic lesions (P = 0.79). MFT was higher in lame cattle with DD compared to non-lame cattle with DD (P = 0.005). Our results demonstrated that all DD affected cattle experience pain as measured using MNT, especially lame cattle who also expressed higher MFT. These are important findings when developing strategies for pain mitigation and detection.