I had to put my mare down last night but we still have no idea what was wrong with her so i thought i would put this out to see if anyone had seen this before. It all started a week and a half ago, my husband and i noticed her laying down in the pasture and decided to check on her, she didnt move and was not really wanting to get up. We called our Vet who promptly showed up, she had no fever and blood work indicated nothing, since she was not rolling or in no pain that we could tell he thought it might be the choke (she has had colic before and it all worked out fine after an all night walk and my wonderful vet), he ran a tube down into her stomach and pumped mineral oil and water in and sucked back out to check, nothing. so she was put on antibotics and anti inflammatory for the time being. She seem to be ok just acted as if she was sedated. We watched her and she stayed in her stall drinking huge amounts of water, still eating but not a lot. guts sounds were all good. so that went on and like i said she seem to be ok just acted sedated, i watched her came home this last monday and she went down again, i got her up and called my vet, he came out and she now was losing weight, we pumped her full of antibotics again and she is now running a very slight temp, checked blood again and still nothing. she slept most of the night and then was back up. Come Wednesday morning i found her down and this time not getting up, i could not budge her all the neightbors nothing was getting her up. she was just too weak to stand and seem to be ok with just laying down, i built a make shift shade over her put a fan on her and waited while giving water trying again and again after allowing her to rest to get her up. once it was apparent we were at the end my vet was called in to help her pass. Now we have sent blood to the labs to see if they can determine anything. We thought poison at first but that should have passed or showed up somewhere. if you have any thoughts they would be greatly appreciated, i have 8 other horses and would hate to have to go through this again it was very hard and we miss her so much.