Chances are you aren't killing or preventing heartworms with the Zimmectin Gold. If you are giving them enough to kill heartworms or larvae, you are taking a chance at overdosing your dog.
I'm no vet by any means, but I don't think ivermectin is necessary in 9 week old pups. It's my understanding that it takes around 6 months for a dog to get invested with larvae and for those larvae to mature into heart worms. I don't give ivermectin to pups until they are 6 months old. Panacur & Strongid should take care of any puppy worms.
Strongid does not kill hookworms.
