Then why would the vet say you can use cat FL, I don't I use the spray for kittens and puppies and I've never had any problems. Makes me wonder if I should now.
Front line being on the outside of the body I wouldn't think would effect the eggs. Flea medicine is one of the top toxins found on people from petting and putting it on their pets.
Not disagreeing just letting you know a vet said it was safe for chickens, the cat frontline. I have used the cat/kitten spray, a few drops on the back of the neck I've read some people do it every three months as a preventive.