I have been unsuccessfully treating this Katahdin ewe with scours for more than a month. About three weeks ago, a fecal exam came back positive for strongly and nothing else. So I gave her ivermectin (sheep drench) and I repeated the dose two weeks later. I have isolated her and put on a dry hay only diet, removed the grains , tried pepto-bismol, probiotic, electrolytes. Nothing works. She has good appetite but is loosing weight. She is a good mother and I want to save her, but I am running out of options. Should I try one more dose of ivermectin? Any advice?