I've never lost a horse myself, but I've known two die from freak accidents in the stable (both broken legs) three PTS through old age, and one from colic.
I have lost 3 over the years. All have been fairly panic free, I seem to have a retirement home for horses, lol.
1 at the grand old age of 45 and he peacefully died in the field.
1 was pts (gun) due to being diagnosed with cancer at the age of 22.
1 was pts (injection) due to falling down and not being able to get up at the age of 25.
Not really any of the above. I'd only had him 6 months at the time he was PTS. He'd been lame on and off for most of that time (bought sound and passed a vetting!) and at the end it turned out he had massive dejenerative problems with his back, pelvis, knees and coffin joints. Without naming names he was bought from a 'reputable' dealer. He was mercifully PTS by lethal injection. Miss you Bertie B.
Mine had an accident in the field. He put his front leg through a 5 bar wooden gate (to this day I still dont know how he managed to do that), panicked, pulled the gate of its hinges and smashed it to smithereens. In the process snapped his front leg clean in half (it was just dangling there, waving about every time he moved) and also shreaded the rest of his legs. He was PTS withing 20 mins of it happening there was nothing that could be done to save him.
I got to page 2 before I burst into tears at my desk must be the weather or something becasuse I am usually the one Who deals with all the death and am usuall OK with it
last year old girl to broken pastern in field also went very very lame behind, no obvoious cause no kick or fall were apparent.
The week before very nearly lost other horse during surgry had a full cardiac arrest vets thought she was brain damaged and would not come round but thankfully made full recover!