Poultry large roundworms will not infect dogs, they are species specific. No worries there at all. However if a dog is infected with hookworms which are a type of roundworm, chickens and humans can be infected. Humans have to go barefooted in order to be infected by hookworms. This is one reason why we worm dogs monthly as a preventative. Valbazen will take care of hookworms in poultry (and dogs, but I wont discuss this at this time.)
There isnt anything that will kill worm eggs once excreted onto the grass except sunlight. The suns UV rays kill exposed eggs. This is why you should keep your grass cut short.
ONE female large roundworm lays thousands of eggs a day onto the soil. Chickens are always pecking the soil and they will pick up the eggs and swallow them. The eggs are eventually excreted and become infective. The infective eggs are picked again and swallowed by chickens. Once matured, it is at this time they reproduce all over again completing its life cycle.
The only way to stop the worms life cycle is to worm monthly. There is no specific time limit when to stop worming monthly. Testing fecal samples monthly will determine if your birds are worm free. Then rotate pasture and/or areas where chickens free range will help reduce worm infections. If you give treats to your chickens; such as scratch, put it on cement, like a paver. Dont put treats on soil where they can pick up worm eggs. Hang feeders over pavers as well, dont let them pick feed off soil. These are simple preventative measures you can take in preventing worm infections.
Penned chickens are more susceptible picking up worm eggs. Adding sand and layering it over time, especially after periods of rain will help control worms. Keeping everything as dry as possible is always best to help control parasites.
Warm, moist or wet soil is very conducive for worms. It is your environment that dictates how often you should worm your birds.
Our soil here is warm and wet most of the year and I worm my birds monthly. I also worm my dog monthly as recommended by his vet. It is up to you if you wish to eat eggs after worming. If you believe that you or a family member might have a reaction to wormer residue in the eggs, toss them in the garbage and do not feed them back to your chickens. Do not sell them nor give them away to anyone after worming. We eat the eggs after worming and I'm still here typing.
The only product that I would toss eggs in the garbage (and have) is Ivermectin. Ivermectin stays in the chickens system for about 30 days, like in a dog. I dont use Ivermectin anymore, it is not an effective wormer in poultry.
Benzimidazoles (Valbazen, Safeguard) are not very well absorbed and are quickly excreted from the chickens system and much safer to use. If anyone wished to toss eggs after using Valbazen or Safeguard, that is fine as well. I used to toss eggs 14 days after last use.
Apple cider vinegar, cucumber seeds, pumpkin seeds, DE etc will not prevent nor treat worms.
