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In the USA, piperazine is no longer approved for use in poultry. Fenbendazole is the only approved drug, and there's no withdrawal time depending on dosage for it. Also, if one bird in the flock has roundworms, all will likely need to be treated. did anything else turn up on the vet's fecal exam? If you are only treating rounds because you actually saw one, and haven't had fecals run, you will be missing the whole story, and failing with piperazine anyway.
Mary
In the USA, piperazine is no longer approved for use in poultry. Fenbendazole is the only approved drug, and there's no withdrawal time depending on dosage for it. Also, if one bird in the flock has roundworms, all will likely need to be treated. did anything else turn up on the vet's fecal exam? If you are only treating rounds because you actually saw one, and haven't had fecals run, you will be missing the whole story, and failing with piperazine anyway.
Mary