Heartgard (ivermectin) For Dogs is used to prevent
canine heartworm disease by eliminating the tissue stage of heartworm larvae
(Dirofilaria immitis) for a month (30 days) after
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:
Chewables Per Month
Color Coding on Foil Backing and
Up to 25 lb
26 to 50 lb
51 to 100 lb
Give dogs over 100 lb the appropriate combination of these
HEARTGARD Chewables are recommended for use in dogs 6 weeks
of age and older.
Administration: 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
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.
Precautions: All dogs should be tested
for existing heartworm infection before starting treatment with HEARTGARD
which is not effective against adult D. immitis.
Infected dogs must be treated to remove adult heartworms and microfilariae
prior to initiating a program with HEARTGARD.
While some microfilariae may be killed by the ivermectin in
HEARTGARD at the recommended dose level, HEARTGARD is not effective for
microfilariae clearance. A mild hypersensitivity-type reaction, presumably
due to dead or dying microfilariae and particularly involving a transient
diarrhea, has been observed in clinical trials with ivermectin after
treatment of some dogs that have circulating microfilariae.
Store between 68°-77°F (20°-25°C). Excursions between
59°-86°F (15°-30°C) are permitted. Protect product from light.
Adverse Reactions: The following adverse
reactions have been reported following the use of Heartgard:
Depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia,
staggering, convulsions and hypersalivation.
SAFETY: HEARTGARD has shown a wide
margin of safety at the recommended dose level in dogs (See PRECAUTIONS for
exceptions) including pregnant or breeding bitches, stud dogs and puppies
aged 6 or more weeks.
Studies with ivermectin indicate that certain dogs of the
Collie breed are more sensitive to the effects of ivermectin administered at
elevated dose levels (more than 16 times the target use level) than dogs of
other breeds. At elevated doses, sensitive dogs showed adverse reactions
which included mydriasis, depression, ataxia, tremors, drooling, paresis,
recumbency, excitability, stupor, coma and death. HEARTGARD demonstrated no
signs of toxicity at 10 times the recommended dose (60 mcg/kg) in sensitive
Collies. Results of these trials support the safety of HEARTGARD products in
dogs, including Collies, when used as recommended.
Keep this and all drugs out of the reach of
Federal (U.S.A.) law restricts
this drug to use by or on the order of a licensed veterinarian