Many years ago we had a quarter mare that went down with what appeared to be colic. Called the vet, he came out, said it was worms. (He had just tubed her the week before.) I yelled at him about this, told him couldn't he remember tubing her, and he said she probably had so many worms they clogged her up. Stupid vet! The mare had a nine or ten day old foal on her side. He would treat the mare, and she would get better, then start all over again. This went on for three days. Finally, the mare was down, and so sick, her foal was stealing from her when he could reach her bag. The vet told my husband that he was going to give her a shot that would kill her or cure her. Said this was only used for cattle. My husband asked him what it was and he said "Calcium". We told him to go ahead as she was down and couldn't get up. He gave her the shot, and she started improving almost immediately. After a few days, she was recovered, (more visits from the vet), and went on to raise that little foal we thought was going to be an orphan. This vet was a friend of my husband's, and they had gone through grade and high school together. He was a small animal vet that wanted to get more into large animals. Needless to say, he did not ever treat any more of our large animals. He did come through in the end, but my gosh the suffering he let that mare, and us go through, before he tried the "cow shot." He never did any blood work either.
Here's hoping your mare will recover as quickly and as well as she.