The welfare of dairy cows is becoming increasingly important. While diseases like mastitis and lameness are common ailments, injuries to the tail tip go largely unnoticed. This study aimed to investigate whether tail tip lesions, which are mostly described in beef cattle, also occurred on n=5 dairy farms, along with determining what type and at what frequency. The study consisted of two phases. During the first part of the study, tail tips of 78 dairy cows were examined over a period of 6 months; based on these results, we developed a training card on tail tip lesions in dairy cows, which was used in part two of the study to train further examiners to inspect four more flocks. In total, we collected n=3587 tail records from n=513 Holstein and n= 128 Simmental dairy cows. The overall frequency regarding all types of lesions ranged between 84.0 % (±2.0) and 94.1 % (±1.8) in Holstein herds and between 97.0 % (±2.2) and 99.0 % (±2.2) in Simmental herds. To our knowledge, this is the first investigation of tail tip lesions in German dairy cows. We concluded that tail tip lesions might be a frequent yet unnoticed condition in German dairy cows.

Tail inflammation and necrosis in dairy cows are increasingly reported, yet the early stages of their development and dynamics remain unclear. We conducted a longitudinal study to characterize the macroscopic pathogenesis of tail lesions throughout the entire lactation period to identify the initial stages and vulnerable phases of lactation. Fifty-one cows were examined weekly. We scored the distal spineless tail for bloody lesions. Change point analysis and first-order Markov chains were used to describe the timing and transitions probabilities. Overall, 60.8% of the cows developed at least one bloody lesion, with 49.0% experiencing lacerations and 25.5% undergoing autoamputation. On average, autoamputation shortened tails by 4.0 cm. Three progression types were identified: laceration with healing and preservation of the tip, autoamputation after laceration and spontaneous autoamputation. Regarding the frequency of occurrence, 65.5% began as bloody lacerations and healed in 93.2% of cases. Of these, 4.0% progressed to autoamputation, 12.7% underwent spontaneous autoamputation from an intact tip. Significant changes in lesion severity occurred in lactation weeks 8 and 40. These patterns are consistent with an endogenous microcirculatory mechanism and support the hypothesis that tail inflammation and necrosis may represent a manifestation of Bovine Inflammation and Necrosis Syndrome.