Okay, say I need to worm my flock (as far as I know, I don't yet, but I expect I will have to at some point). Say I use either ivermectin or fenbendazole. I understand that the withdrawal period is two weeks. Throwing out two weeks worth of eggs would really twist my knickers. Now, I have four dogs and three cats. When I worm them, I use fenbendazole, which has a very wide margin of safety. The dogs get ivomec for heartworm control. (They are all MDR1 normal/normal, so this is safe for them.) If I worm the chickens with the same products is there any reason the dogs can't eat all those eggs? I've thought about the risk of encouraging resistance in the dogs' parasites if they get two weeks of a very low exposure to an antithelmintic via the eggs for two weeks. So what if I worm everyone -- dogs, cats, chickens -- at the same time, so that there are theoretically no intestinal parasites in the dogs to develop resistance as they eat the eggs for the next two weeks? Is this reasoning sound?