My vet used to work for Tyson Chickens as their vet. He advised me to bring in a stool sample if I suspected a chicken might have worms. There is more than one kind of worm they can get, and the chicken should be treated for whatever kind it has. Some folks worm very often with Wazine which I think only kills roundworms. Others use Ivermectin which I think kills them all, but my vet said it's sort of crazy to worm a chicken that doesn't need worming. I tend to agree, although the stool sample test per bird is $12! Although there is no proof that food grade Diatomaceous Earth actually gets rid of worms, some say it does or at least is a deterrent. It is organic and safe to dust chickens for lice and mites as well as the coop and nest/laying boxes. It is also safe for chickens to eat in small quantities. I mix a teaspoon a week in cooked old fashioned oatmeal with plain probiotic yogurt and feed to my flock. They love it, and not one of them has runny poo constantly and none have given me reason to suspect worms. I also put a Tablespoon of apple cider vinegar in every gallon of water they drink. That is supposed to be good for relieveing stress and other beneficial things. If your birds don't free range, they are less likely to get worms. I only have one at this time who free ranges. She is full of energy and lays 5 or 6 eggs a week, so I don't suspect a problem. If and when I do, I'll take a stool sample to the vet.
