Heartgard must be administered monthly, preferably on the same date each month. It is recommended(and most manufacturer guarantees require) that Heartgard be given year round, although some veterinarians may recommend giving it only during the mosquito season. If given seasonally, the first dose must be given within 30 days of the cat's first exposure to mosquitoes. The last dose must be given within 30 days after the cat's last exposure to mosquitoes.
Most cats will accept the chewable tablet as a treat. The chewable should be administered in a manner that encourages the cat to chew, rather than to swallow without chewing. Heartgard Chewables may be broken into pieces and fed to cats that normally swallow treats whole or may be mixed with a small amount of cat food. Food should be available during the day of treatment. If the cat does not eat or the chewable is not broken, the medication may not be well-absorbed. Care should be taken that the cat consumes the complete dose, and treated animals should be observed for a few minutes after administration to ensure that part of the dose is not lost or rejected. If not entirely consumed, give another full recommended dose as soon as possible.