Hoof flares are an abnormal widening of the walls of the hoof, usually occurring at the heel area. The cause of this condition is typically due to incorrect trimming or shoeing techniques which can lead to increased strain on certain parts of the hoof wall. If left untreated, it can lead to pain and lameness in horses. Poor nutrition and a lack of exercise can also play a role in contributing to hoof flares as they can weaken or damage the hooves over time. Additionally, genetics may be responsible for some cases as well since some breeds have naturally weaker feet that are more susceptible to developing this issue.