Worming with syrup

Drontal syrup I have bred for 50 years and had litter that u worm every two weeks used the Troy syrup never a problem then decided go to drontal to my horror I used used the tablets on my 6 weeks pups and I nearly lost a pup blocking the air ways on her with a live worm Chocking her she survive only through quick thinking on my. Part I will use drontal syrup again. Breeders take note.