It can be used for dogs and puppies six weeks of age and older

Of course you can. Please place an order for 12 packs with 3 or 6 months auto refill plan. Then contact our support team (support(at)petbucket.com).They will happily change your recurring order period to 12 months or anything you would like.

Valuheart treats heartworm only. Discontinued, Interceptor Spectrum and Revolution/Stronghold are a some products that do prevent roundworm. http://goo.gl/ZBDH4R Thanks for our inquiry!

No, You don't need prescription for it.

The active ingredient is Ivermectin and you might like ot see all FAQ's here http://www.valuheart.com/faqs/