
Hi Kate
Welcome to the forum. :-) Frontline spot on is a definite no for a pregnant bitch. And Frontline spray is ok - but why would you want to Frontline? I never routinely use a flea treatment on my dogs, and only resort to Frontline spray when I see one of the little beggars. And I have not used it in almost 5 years. So it does depend on the individual dog. I can't be the only breeder that never sees fleas. I guess, to a certain extent, it does depend on where the dogs are exercised.
However, I once had a pregnant bitch - only found one flea on her - but blasted with Frontline spray and drowned the blighter. She whelped with no problems, and it didn't hurt her unborn pups. I wouldn't however, blast a bitch with chemicals if she didn't have fleas.
I too Drontal my bitches prior to mating, but this has nothing to do with the worms that bitches get just because they are pregnant.
ALL bitches have encysted worms that are woken up by pregnancy hormones. That is why you start worming at day 40 of gestation, until 2 days post whelp. Panacur 10% suspension is licensed for use in pregnant bitches, and is my wormer of choice. This means that pups are born 98% worm free, so all they have to do is thrive. :-) I have used it for many years, and start pups on it at 14 days. When you say that you didn't worm the bitch during pregnancy last time, and didn't have problems, your puppies would still have been born with a worm burden. I've actually known one breeder of Cairns that lost a whole litter due to a horrendous worm burden. There is no excuse for it!