Even a well-planned transition throws up bumps. Sensitive soles: the solution is rarely rest but protection plus movement — boots for riding, possibly glue-on pads. Uneven growth: frequent trimming, small corrections often. The handbrake: with persistent lameness, strong digital pulse, heat or rapid worsening, relieve the load, contact the farrier, then the vet if it does not turn around. Never wait out a lame horse.
