Heartworm preventatives or prevention medication products should be prescribed by your veterinarian to ensure that your pet does not suffer from any type of adverse reactions. Ideally, the product should be easy to administer, effective, safe, and available at a reasonable price. Your veterinarian will compute the proper dosage for your pet based on the animal’s weight or age. There are heartworm preventatives that can prevent both fleas and heartworms; you can also choose a product that is easiest to give, such as a pill or topical ointment. Your preferences will be considered by your veterinarian when choosing the right heartworm medication for you pet. Most products will need to be given monthly for maximum protection. A product that is labeled for use in dogs should not be given to cats.All the instruction given by your best veterinarians Troutville, VA regarding dosaging and administration should be followed to the letter to avoid adverse reactions.