My girls appear to all have gapeworm and I'm wanting to treat them with Ivermectin. I'd like to add it to their drinking water but am having a hard time coming up with dosages. And does anyone know if I'd buy the pour or the injectable? There's so much info out on the web -- 1%, 5%, pour on, injectable... I'm lost! But I'd like to get them started on a treatment today if possible and will need to stop by Tractor Supply within the next few hours to buy something that works. Thanks!