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.