Honey - please don't blame yourself. You did the best you knew to do for your girl.
We had two horses that we "killed with kindness." We were trying to put weight on them, and were feeding them alfalfa pellets. The more weight they would lose, the more pellets we would add - along with beet pulp and oats. The mare passed away New Year's Eve of 2009. She'd been eating like crazy, but losing weight. The vet said she had elevated liver enzymes, and we were feeding per his recommendations, but eventually we lost that battle.
We had her colt on the same feed regimen, and he kept losing weight and just was not growing. At three years old, he was quite a bit smaller than his yearling sister, even though they were out of the same sire and their dams were close to the same size. Vet said he had elevated liver enzymes, but still recommended the feed program we were using, with some added fats.
Got a new vet, who advised that the alfalfa was most likely what was causing the liver problems - along with some sort of metabolic disorder. He recommended no alfalfa whatsoever - no pellets, and no feeds containing alfalfa. Colt got a little better - gained a little weight...then couldn't get up the other day.
Vet came out and tried for nearly an hour to get the colt to his feet. Then the vet noticed odd tremors in various muscles...it was HYPP, and some sort of hereditary liver disorder. Little guy never stood much of a chance, but he'd have had at least some sort of chance if we hadn't been giving him so much alfalfa.
We blame ourselves for killing not one...but TWO horses.
We don't feed alfalfa any more. Not that we shy away from feeds that might contain it, but it's no longer a mainstay of our horse's diet.
The shame is not in having a horse die - the shame is in repeating the mistakes and causing the death of another horse. That's what we have to live with, and it's not a mistake we will repeat...
Plain Old Dee, horses Dancer and Rain I believe in dragons, unicorns, good men and other mythical creatures!