Hi, If the horse drops feed and takes a long time to eat, look in the mouth again for a tooth abscess, a foreign object in the mouth, or sharp points that were missed. How do you know it does not need it’s teeth floated. Have another dental exam, then if that is found to be okay then do the blood work. I had a friend that had a mare with the same problems and when the vet looked in the mouth (again) there was a piece of wire imbedded in the teeth and jaw that the horse probably had ingested with the hay and it was stuck causing pain with eating, therefore the slowness and weight loss, and dropped feed. Just an idea.