system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:why are horses put down if they break a leg while other animals are looked after?
gpt
Horses legs, compared to the rest of their body are lighter, for speed, so when they break, a lot of times they shatter. When that happens, it's almost impossible to repair. The bones actually bends before it breaks (plastic deformation) so even if you tried to repair it, it would be bent. There is very little soft tissue  there, so a break usually is an open fracture. Living tissue needs blood, and in a open fracture the blood supply is damaged. They need all four legs to support in excess of 1000 lbs, so if they try to compensate for healing, they can end up with laminitis. You can't use a sling to support the leg, because they will get sling sores, and the pressure from the sling can damage the intestinal tract. There's no way to get a horse to lie down for weeks, impossible, and even if you could, they would get pneumonia.