We'll assume that this mare had bucked shins as a young racehorse and is now sound. If this is the case, she should be fine. Bucked shins (microfractures of the anterior cannon bones in the front legs) are a very common occurrence in young racehorses, and once the microfractures are healed, there are no long-term concerns. However, if she is currently sore, something else is going on. Also, if she is somewhat swollen on the anterior (front) aspect of her cannon bone and is sore when pressure is placed on that area, she needs to have a complete lameness exam, including radiographs to rule out a potential "saucer" fracture of the cannon bone.