I never accept the results of a negative fecal, I have to run it a second time to be sure.And pyrantel is no longer on that extremely short list of approved drugs for chickens. Negative fecals are the best that can be done, short of necropsy, so here we are. Most of the time, fecals will pick up something, although doing fecal egg counts are notoriously unrelated to actual worm burdens.
If only having a crystal ball actually worked!
Mary