Prevalence and distribution of hoof lesions in Southern Italian dairy farms adopting regular hoof trimming between 2016 and 2020: A retrospective observational study

Lameness, primarily caused by hoof lesions, is a major concern for the dairy industry. Although regular hoof trimming is widely used as part of prevention and treatment, its long-term effects are not fully understood. This retrospective study investigated 10 dairy farms in Southern Italy that transitioned from irregular (when cows showed signs of lameness or overgrown hooves) to regular hoof trimming (approximately every 6 mo in lactating cows) between 2016 and 2020. The first objective was to estimate the prevalence and types of hoof lesions, and the second was to assess how lesion risk changed over time following the implementation of regular hoof trimming. Lesions were classified into 3 categories: infectious (INF), claw horn disruptive (CHD), and all lesions combined (ALC). Generalized additive mixed effect models (GAMM) with a binomial family and logit link were fitted to model each lesion probability over time. A total of 14,438 individual-level inspections were performed (4,329 unique cows; 57,752 individual hooves) across 113 hoof trimming sessions, with a median time of 159 d (range: 36–338 d) between trimming sessions. Out of 4,329 unique cows inspected, 2,773 (64.1%) had at least one lesion during the study period; 38.0% (1,643/4,329) had at least one INF lesion and 47.0% (2,035/4,329) had at least one CHD lesion. The most common lesions were white line disease (59.4%) and digital dermatitis (58.2%). Lesion risk followed distinct temporal patterns: CHD lesions exhibited a nonlinear trajectory, declining from ∼17% to ∼7% by d 1,000, then rising to ∼10% after d 1,500. Infectious lesions declined linearly from 15% to 5% over the same period. All lesions showed an early decline from ∼30% to ∼17% to 25% between d 500 and 1,000, followed by stabilization. Seasonal variation was observed to have a modest but consistent effect, with predicted lesion risk modestly higher in winter months compared with summer months. Rear hooves consistently had higher predicted lesion risks than front hooves across all models. Substantial farm-level variability was also observed, highlighting the importance of tailored, herd-specific management approaches. In light of the observational study design, caution is required when interpreting these findings with respect to the hoof trimming interval. Further research using controlled designs is warranted to optimize trimming protocols and identify additional risk factors.