There is no escaping the truth of this:
"And finally Boss, if I am in pain
or when my useful strength has gone;
Do not turn me out to starve
or freeze or send me on to owners new;
They did not know me in my prime.
You did, my Master,
you should end my life when the day has come,
in a quick and painless way."
There is more on a thread entitled
"Joe's prayer" back in the Forum "Poems"
Sadly it is the price sometimes we must pay for knowing and loving horses.