A promising young horse gets loose from his paddock one evening, gets tangled in a wire fence, spooks, and the wire cuts deep enough to sever the tendons of his hind leg: the damage irreparable, he is euthanized because his owner couldn't be bothered to repair the paddock gate.
A dressage contender gets out of his stall, wanders into the cement-floored hay barn, spooks, slips on the cement, falls, and tears all the ligaments in his hind legs: he's euthanized because the owner was stupid and couldn't be bothered to replace a $2 stall latch.
On a foggy night, a neighbor with a grudge opens a friend of mine's pasture gate, allowing my friend's father's four horses to wander out on the highway: in the fog, three are hit by a semi, crippled but not killed, screaming in pain along the highway, and need to be euthanized.
A woman doesn't want to be bothered with the increased demands of her older mare --senior feed three times a day instead of hay twice a day-- even though the mare is otherwise in good condition: she has the perfectly healthy mare euthanized out of laziness.
By pure shitty, rotten, fucked up chance, a mare newly recovered from laminitis, back in good health, is struck by strangulating lipoma: a strand of fat wraps around her small intestine, blocking bloodflow. The call comes through at 3:30 in the morning; the mare is writhing in agony in the pasture. The vet gets the mare up and works wonders to get her to surgery, two hours away including a ferry ride, but 80% of the mare's intestine is dead and despite a top-tier surgical team and the best of care throughout the mare's life, there's nothing to do: not even 23 years old, the mare is euthanized.
Day after day, around the clock, my vets got calls like these. Beautiful, gentle, generous creatures in agony, with no option but euthanasia. I don't know how the vets did it.
That last case was my beloved mare, my "mare-daughter," and I spent the next week ready to end my own life. How the vets survive as well as they do, I'll never know.