I use drontal for my golden retriever and he's not had worms on them. He doesn't get them at the vets, purely because we can buy them cheaper and in bulk online, our vets tend to rip us off! It was the vets who started him on them and gave them his first lot though. I wouldn't trust anything you can buy over the counter in a supermarket, not ever! They will be a rip off and do nothing, or incredibly cheap, and do nothing! Its something I think you should ask your vet about first for a brand type, they will have a good idea on which brands are best.

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