My Old Man is “pasture sound” with lameness that never gets better and it never gets worse (even when he’s ridden, or even jumped lightly).
I know what it is. I’m sure other parts of his body have gotten worse due to the original lameness cause, but I haven’t pursued them. I’ve spent LOTS of money to get him sound, and I’m not going to spend any more. I’ve even taken him off of equioxx as of late, because he’s beyond the point of help.
For me, I watch him every time he rolls. The day it takes him multiple tries to get up, I will make the appointment.
ETA: My Old Man is 25 though, can still be ridden WTC and on trails etc, is an easy keeper, etc. I’ve had him since he was 3, we competed in 4’ jumpers for many years before he had to step down. It’s not the same as the 5 year old lame horse. As bad as it sounds and as hard as it is to explain, I’d euth the 5 year old faster than my Old Man. I feel like I owe my Old Man his golden years. I would not feel the same about a younger horse.