I believe the last hen I rescued has gape worms. I am afraid to use a wormer made for cows or any other large livestock. It says on the label, "Do not use on any birds that are extremely ill." Therefore, I assume it is ok for chickens (healthy ones that is). Will Ivomec Drench Liquid get rid of the gape worms? What is the dosage? Anything else I should know before trying it? Thanks in advance!