Horses with broken legs are often euthanized because their injuries are very difficult to heal and they pose significant welfare issues. Here are the main reasons why horses with broken legs are usually not saved:

1. Anatomy and Physiology: Horses are large animals that rely almost entirely on their legs for mobility and weight-bearing. Unlike humans and some other animals, horses’ legs are not built to withstand the stress of supporting their body weight while healing from a fracture. The bones in a horse’s legs are slender and subjected to enormous forces during movement. Healing in a cast or splint is problematic due to the size and weight of the horse and the constant stresses placed on the limb.
2. Nature of Fractures: Horse leg fractures are often compound, open, or comminuted, meaning the bone is shattered into multiple pieces or exposed to the environment, which increases the risk of infection and complicates treatment.
3. Complications During Recovery: Even if surgery is attempted to repair the fracture, the recovery period is long, painful, and fraught with complications. Horses confined to stall rest for extended periods are prone to serious health problems such as laminitis (a painful hoof condition) and pneumonia due to reduced mobility.
4. Quality of Life: A horse unable to stand or walk for an extended period faces poor quality of life. They are highly social and active animals that require movement for their physical and mental well-being. Long-term immobilization is extremely distressing for them.
5. Financial Considerations: Treating equine limb fractures often involves costly and advanced veterinary procedures, which many owners cannot afford. Even with the financial resources, the success rate of returning a horse to its former level of function is low.
6. Ethical Considerations: Veterinarians prioritize animal welfare and the prevention of unnecessary suffering. Euthanasia is often the most humane choice given the challenges of treating a horse with a broken leg and the low likelihood of a successful outcome.

In summary, while advances in veterinary medicine continue to evolve, the nature of horse anatomy, the severity of leg fractures, and the difficulty of rehabilitation mean that euthanasia remains a common course of action to prevent prolonged suffering.