Hock lesions are common skin alterations in dairy cows. Previous studies have primarily focused on prevalence and respective risk factors. The precise impact of hock lesions on dairy cows health and welfare, e.g. in terms of pain and suffering, is largely unknown. In order to investigate the relevance of hock lesions for dairy cows welfare, we investigated signs of inflammation, especially hyperthermia and the presence of inflammatory cells through thermal imaging and histological methods. We assumed that already mild hock lesions, indicated by hair loss, are relevant for an animals welfare. The first study was carried out in cooperation with the University of Life Science Warsaw on a free-stall dairy farm in Poland. 172 tarsal joints of lactating dairy cows were investigated during milking. Two locations (hock and point of the hock) were visually scored on a four point categorical scale and thermal images (FLIR T440) were taken. The second study comprised visual scoring and histological examination of 25 hocks and 26 points of the hock of dairy cows; sampling was carried out at an abattoir in Austria and histological evaluation was performed in cooperation with the University of Veterinary Medicine in Vienna. In the first study (visual and thermographic examination) an increase in hair loss (in terms of size of the area affected) resulted in an increase in skin temperature. This effect became more evident at hocks and points of the hocks that additionally showed ulceration. In the second study already mild hair loss (no hair loss) was followed by mild tissue alterations. Moreover, an increase in hair loss was mostly reflected in an increased inflammatory response. These findings support our hypothesis that already mild hock lesions are followed by signs of an inflammation and are therefore relevant for dairy cows health and welfare. However, further research regarding painfulness, temporal development and aetiology of hock lesions in dairy cows is needed.