Heartgard® (ivermectin) Chewables should be administered orally at monthly intervals at the recommended minimum dose level of 6.0 mcg of ivermectin per kilogram (2.72 mcg/lb) of body weight. (See ADMINISTRATION). The recommended dosage schedule for prevention of canine heartworm disease is as follows:
|Dog Weight ||HEARTGARD® for Dogs |
Chewables per month
|Up to 25 lbs ||1 ||68 mcg |
|26 to 50 lbs ||1 ||136 mcg |
|51 to 100 lbs ||1 ||272 mcg |
Give dogs over 100 Ibs the appropriate combination of these chewables.
Heartgard® Chewables are recommended for use in dogs 6 weeks of age and older.
Remove only one chewable at a time from the foil-backed blister card. Return the card with the remaining chewables to the box to protect the product from light. Because most dogs find Heartgard® Chewables palatable, the product can be offered to the dog by hand. Alternatively, it may be added to a small amount of dog food. The chewable should be administered in a manner that encourages the dog to chew, rather than to swallow without chewing. Chewables may be broken into pieces and fed to dogs that normally swallow treats whole. Care should be taken to see that the dog 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 it is suspected that any of the dose has been lost, redosing is recommended.
Heartgard® Chewables should be given at monthly intervals during the period of the year when mosquitoes (vectors), potentially carrying infective heartworm larvae, are active. The initial dose must be given within a month (30 days) after the dog's first exposure to mosquitoes. The final dose must be given within a month (30 days) after the dog's last exposure to mosquitoes. When replacing another heartworm preventive in a heartworm disease preventive program, the first dose of Heartgard® must be given within a month (30 days) after the last dose of the former medication.
If the interval between doses exceeds a month (30 days), the efficacy of ivermectin can be reduced. For optimal performance, the chewable must be given once a month on or about the same day of the month. If treatment is delayed, whether by a few days or many, immediate treatment with HEARTGARD® and resumption of the recommended dosing regimen minimizes the opportunity for the development of adult heartworms.