Package Insert Top
(Ivermectin and Pyrantel)
Caution: Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian.
INDICATIONS: For use in dogs to prevent canine heartworm disease by eliminating the tissue stage of heartworm larvae (Dirofilaria immitis) for a month (30 days) after infection and for the treatment and control of ascarids (Toxocara canis, Toxoscaris leonina) and hookworms (Ancylostoma caninum, Uncinaria stenocephala, Ancyclostoma braziliense).
DOSAGE: Tri-Heart® Plus ivermectin/pyrantel chewable tablets should be administered orally at monthly intervals at the
recommended minimum dose level of 6 mcg of ivermectin per kilogram (2.72 mcg/lb) and 5 mg of pyrantel (as
pamoate salt) per kg (2.27 mg/Ib) of body weight. The recommended dosing schedule for prevention of canine
heartworm disease and for the treatment and control of ascarids and hookworms is as follows:
|Color Coding on
Blister Card and Carton
|Up to 25 lbs.||1||68 mcg||57 mg||Blue
|26 to 50 lbs.||1||136 mcg||114 mg||Green
|51 to 100 lbs.||1||272 mcg||227 mg||Brown
Tri-Heart® Plus ivermectin/pyrantel chewable tablets are recommended for dogs 6 weeks of
age and older. For dogs over 100 lbs, use the appropriate combination of these tablets.
ADMINISTRATION: Remove only one chewable tablet at a time from the blister card.
Because most dogs find Tri-Heart®t Plus chewable tablets palatable, the product can be
offered to the dog by hand. Alternatively, it may be added intact to a small amount of dry food
or placed in the back of the dog’s mouth for forced swallowing.
Care should be taken 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.
Tri-Heart® Plus chewable tablets 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
When replacing another heartworm preventive product in a heartworm disease preventive
program, the first dose of Tri-Heart® Plus chewable tablets must be given within a month (30
days) of the last dose of the former medication.
If the interval between doses exceeds a month (30 days), the efficacy of ivermectin can be
reduced. Therefore, for optimal performance, the chewable tablet 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 Tri-Heart® Plus chewable tablets and resumption of the
recommended dosing regimen minimizes the opportunity for the development of adult
Monthly treatment with Tri-Heart® Plus chewable tablets also provides effective treatment
and control of ascarids (T. canis, T. leonina) and hookworms (A. caninum, U. stenocephala,
A. braziliense). Clients should be advised of measures to be taken to prevent reinfection with
EFFICACY: Tri-Heart® Plus chewable tablets given orally using the recommended dose and
regimen, are effective against the tissue larval stage of D. immitis for a month (30 days)
after infection and, as a result, prevent the development of the adult stage. Tri-Heart®
Plus chewable tablets are also effective against canine ascarids (T. canis, T. leonina)
and hookworms (A. caninum, U. stenocephala, A. braziliense).
ACCEPTABILITY: In acceptability trials, Tri-Heart® Plus chewable tablets were shown to be
a palatable oral dosage form that was consumed at first offering by the majority of dogs.
PRECAUTIONS: All dogs should be tested for existing heartworm infection before starting
treatment with Tri-Heart® Plus chewable tablets which are not effective against adult
D. immitis. Infected dogs must be treated to remove adult heartworms and microfilariae
before initiating a program with Tri-Heart® Plus chewable tablets.
While some microfilariae may be killed by the ivermectin in Tri-Heart® Plus chewable
tablets at the recommended dose level, Tri-Heart® Plus chewable tablets are 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 alone after treatment of some dogs that have
Keep this and all drugs out of the reach of children. In case of ingestion by humans, clients
should be advised to consult a physician immediately. Physicians may contact a Poison Control Center for
advice concerning cases of ingestion by humans.
ADVERSE REACTIONS: In clinical field trials with ivermectin/pyrantel, vomiting or diarrhea
within 24 hours of dosing was rarely observed (1.1% of administered doses). The following
adverse reactions have been reported following the use of ivermectin at the recommended
dose: depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering,
convulsions and hypersalivation.
SAFETY: 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 of 6 mcg/kg) 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. Ivermectin
demonstrated no signs of toxicity at 10 times the recommended dose (60 mcg/kg) in sensitive
Collies. Results of these trials and bioequivalency studies support the safety of
ivermectin products in dogs, including Collies, when used as recommended.
Ivermectin/pyrantel has shown a wide margin of safety at the recommended dose level in
dogs, including pregnant or breeding bitches, stud dogs and puppies aged 6 or more
weeks. In clinical trials, many commonly used flea collars, dips, shampoos,
anthelmintics, antibiotics, vaccines and steroid preparations have been administered
with ivermectin/pyrantel in a heartworm disease preventive program.
In one trial, where some pups had parvovirus, there was a marginal reduction in efficacy
against intestinal nematodes, possibly due to a change in intestinal transit time.
Store at controlled room temperature of 59·860 F (15·300 C). Protect product from light
HOW SUPPLIED: Tri-Heart® Plus chewable tablets are available in three dosage strengths (See
DOSAGE section) for dogs of different weights. Each strength comes in convenient packs of 6
For Technical Assistance, call Merck Animal Health: 1-800-224-5318
Manufactured for: Intervet Inc. a subsidiary of Merck and Co. Inc., Summit, NJ 07901
Manufactured by: Diamond Animal Health, Inc., a wholly owned subsidiary of Heska Corporation,
Des Moines, IA 50327
©2013 Heska Corporation. All rights reserved.
ANADA 200-338, Approved by FDA
25 lb unit carton
25 lb display carton
26-50 lb unit carton
26-50 lb display carton
51-100 lb unit carton
51-100 lb display carton
Intervet, Inc. a subsidiary of Merck and Company, Inc.