Know that gapeworms can contaminate the coop and run area for the next 5 or more years. The eggs survive in the ground dwelling critters like earthworms. I agree it is a horrible way to die, gasping for breath. My Dad has issues with this a couple years ago and ended up moving his coop to a whole other area of land. I do wish you the best of luck. Have you confirmed with necropsy that it was indeed gapeworm? If you still have the carcass, I recommend opening her up to check for the worms in her trachea.