We give Safeguard at higher doses than normally quoted for use in water for three days and find it to be effective in worming with no harmful effects and NO loss of fertility in our tests. I would guess we would have seen feather issues if they existed. Of course most all worming effectiveness is circumstantial since it is not practical to actually measure some types of worm loads (capillary/cecal).
Fenbendazole is obviously has a high factor of safety with regards to dosage. The fertility thing with regards to fenbendazole is something that has grown legs and become legend. We have not specifically tested Valbazen with regards fertility but we have heard that it both does and does not cause infertility from folks we would trust.
My husbands weiner dog passed some round worms after being on heartguard all his life and i questioned the vet about that as the meds were supose to keep them away and i asked if it was ok to go ahead and worm him with safeguard sence he had already had his meds and the vet informed me that there is a reason it is called safeguard, it is very hard to overdose an animal on it and it was ok to use it on Tobie even though he had his heartguard recently.
True... It's used in cats, kittens, dogs, puppies, foals, pregnant mares, breeding stallions, calves, cows, bulls, pigs, sheep, goats, ect. (basically all mammals), all types of birds and reptiles. The lethal dose in mice and rats is huge, much greater than all other wormers I have read about. I'm not positive, but I believe it doesn't have any drug interactions either, which makes it an ideal choice for treating our peas when we aren't quite sure what they might have (blackhead, coccidiosis, E. Coli, worms or a combo of problems).
-Kathy