The term ‘sore shins’ or ‘bucked shins’ is a training injury term familiar to racehorse owners, but what is it?
Shin soreness, put simply, is bony remodelling and associated pain on palpation over the dorsal aspect of the third metacarpal bone, or the front of the cannon bone. It commonly affects 2-year-old racehorses (and less commonly affects older horses) in their early racing preparations and can account for a significant percentage of lost training days in young horses.
As bone is dynamic, adaptive and changes under stress, the process of bone modelling and/or remodelling can be a normal clinical response to training. The porous third metacarpal bone thickens where new bone is laid down, becomes stronger and helps resist mechanical loading in the dorsal direction. However, during this process of remodelling there is a period where the bone is structurally weaker in the reabsorption phase (osteoclastic activity, which is the process of bone reabsorption, is painful) and in periods of increased demand, can lead to a periostitis. This presents clinically as ‘sore shins.’
Our team of veterinarians use regular trot-ups and clinical examination to detect any superficial pain or swelling. Radiographs may also be beneficial to confirm periosteal new bone formation and to rule out dorsal cortical stress fractures. If signs of shin soreness develop, the team develop a controlled plan of work load, managing inflammation and advise on nutritional supplementation where required.
What needs to be clear is that shin soreness is a normal part of the development and conditioning of the bone, this process enables the bone structures to become reinforced to support your horse over their racing career.
Image 1: Bone remodelling in the third metacarpal bone retrieved from http://www.horsedvm.com/disease/bucked-shins/ on 18th August 2021.