People sometimes use the injectable on their dogs, however, they are usually giving them a dose that is hundreds of times more than is needed. This is because it is meant for livestock that are hundreds to thousands of pounds, and therefore very concentrated. It is the same drug that is used in Heartguard/ProHeart and prevents infection of heartworms. Heartgaurd Plus has an additional drug (pyrantel) which kills roundworms and hookworms. I would caution you to use this the livestock Ivomec, especially if you have a collie. The low dose in an approved heartworm preventative is very safe, but the livestock formulas can be lethal due to the high dose, especially in collies. If you insist on using it, please take it to your vet and have them calculate the dosage for you to be safe. Tapeworms need to be treated with a special drug as they are not affected by pyrantel. This is best avoided by using a good flea treatment on your dog such as Comfortis or Advantage (if it still works for you). The tapeworm treatment is a one time dose (and quite expensive), so if the dog ingests a flea again he may be reinfected with tapeworms.