Caution: Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian.
For use in cats to prevent feline heartworm disease by eliminating the tissue stage of
heartworm larvae (Dirofilaria immitis) for a month (30 days) after infection, and for the removal and control of
adult and immature hookworms (Ancylostoma tubaeforme and A. braziliense).
HEARTGARD for Cats should be administered orally at monthly intervals at the recommended
minimum dose level of 24 mcg of ivermectin per kg (10.9 mcg/lb) of body weight.
For cats over 15 lb, use the appropriate combination of chewables.
HEARTGARD for Cats is recommended for use in cats 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 its box to protect the product from light. HEARTGARD for Cats can be
offered to the cat by hand or may be added to a small amount of cat food. If manual dosing is required, the
chewable should be broken into pieces for administration. Food should be routinely available during the day of
treatment administration. If cats are fasted, or if the chewable is not broken into pieces for manual dosing, then reduced absorption may result. A relationship between reduced absorption and reduced efficacy has not been established.
Care should be taken to see that the cat consumes the complete dose. 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 with a new chewable is recommended. Fragments of chewables have
occasionally been observed in the feces of some cats; efficacy of the product was not adversely affected.
HEARTGARD for Cats should be given at monthly intervals when mosquitoes potentially carrying infective
heartworm larvae are active. The initial dose must be given within a month (30 days) after the cat’s first
exposure to mosquitoes. The final dose must be given within a month (30 days) after the cat’s last exposure to
mosquitoes. For optimal performance, HEARTGARD for Cats must be given once a month on or about the
same date. If treatment is delayed, whether by a few days or many, immediate treatment with HEARTGARD
for Cats and resumption of the recommended dosing regimen will minimize the opportunity for development of
It is recommended that cats should be tested for existing heartworm infection prior to starting treatment with
HEARTGARD for Cats. Cats already infected with adult heartworms can be given HEARTGARD for Cats
monthly to prevent further infections.
Monthly treatment with HEARTGARD® (ivermectin) for Cats also provides effective removal and control of adult and immature hookworms (A. tubaeforme and A. braziliense).
In the clinical studies involving more than 3000 doses of HEARTGARD for Cats, observations
reported within 24 hours of treatment included vomition in ≤ 0.3% and diarrhea in ≤ 0.2% of the doses
administered. There were no statistical differences between HEARTGARD for Cats and the product vehicle
(control) for these observations.
A wide margin of safety was demonstrated in clinical trials at the recommended dose level in cats and kittens 6
weeks of age and older and in laboratory studies in cats with circulating microfilariae of D. immitis. A wide
margin of safety has also been demonstrated at 3 times the recommended dose in pregnant or breeding queens
and breeding toms. No adverse effects were observed in either male or female cats or their offspring in breeding
studies. A 30-fold safety margin over the minimum recommended dosage was established in a single dose
tolerance study. In growing kittens dosed monthly for 8 consecutive doses, one cat given 5 times the market
dose vomited and a second cat in this group experienced diarrhea within 24 hours of the initial treatment. In
clinical trials, many commonly used flea control products, anthelmintics, vaccines, antibiotics and steroid
preparations were administered with HEARTGARD for Cats without incident.
Keep this and all drugs out of the reach of children. In case of ingestion by humans, clients should be
advised to contact a physician immediately. Physicians may contact a Poison Control Center for advice
concerning cases of ingestion by humans.
HEARTGARD Chewables for Cats are stable for 3 years when stored below 77°F (25°C) and
protected from light. Store at controlled room temperature of 68°F-77°F (20°C-25°C). Excursions between
59°F-86°F (15°C-30°C) are permitted.