Ivermectin and pyrantel

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 roundworms ( Toxocara canis, Toxascaris leonina ) and hookworms ( Ancylostoma caninum, Uncinaria stenocephala, Ancylostoma braziliense ).

Dosage and Administration

VetriShield Plus™ (ivermectin/pyrantel) Flavored Chewables 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/lb) of body weight. The recommended dosing schedule for prevention of canine heartworm disease and for the treatment and control of roundworms and hookworms is as follows: Dog Weight Flavored Chewable Per Month Ivermectin Content Pyrantel Content Up to 25 lbs 1 68 mcg 57 mg 26 to 50 lbs 1 136 mcg 114 mg 51 to 100 lbs 1 272 mcg 227 mg VetriShield Plus™ Flavored Chewables are recommended for dogs 6 weeks of age and older. For dogs over 100 lbs use the appropriate combination of these Flavored Chewables. ADMINISTRATION: 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. Because most dogs find VetriShield Plus™ Flavored Chewables palatable, the product can be offered to the dog by hand. Alternatively, it may be added intact 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 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. VetriShield Plus™ Flavored 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 product in a heartworm disease preventive program, the first dose of VetriShield Plus™ Flavored Chewables 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 flavored 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 VetriShield Plus™ Flavored Chewables and resumption of the recommended dosing regimen minimizes the opportunity for the development of adult heartworms. Monthly treatment with VetriShield Plus™ Flavored Chewables also provides effective treatment and control of roundworms ( 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 intestinal parasites. EFFICACY: VetriShield Plus™ Flavored Chewables, 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. VetriShield Plus™ Flavored Chewables are also effective against canine roundworms ( T. canis, T. leonina ) and hookworms ( A. caninum, U. stenocephala, A. braziliense ). ACCEPTABILITY: In a trial in client-owned dogs, VetriShield Plus™ Flavored Chewables were shown to be a palatable oral dosage form consumed at first offering by the majority of dogs.

Warnings

Use product on or before its expiration date. Discard or return unused tablets.

Precautions

All dogs should be tested for existing heartworm infection before starting treatment with VetriShield Plus™ Flavored Chewables, which are not effective against adult D. immitis . Infected dogs must be treated to remove adult heartworms and microfilariae before initiating a program with VetriShield Plus™ Flavored Chewables. While some microfilariae may be killed by the ivermectin in VetriShield Plus™ Flavored Chewables at the recommended dose level, VetriShield Plus™ Flavored Chewables 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 circulating microfilariae. 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.

Adverse Reactions

In clinical 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: Depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions and hypersalivation. To report suspected adverse drug events, for technical assistance or to obtain a copy of the Safety Data Sheet (SDS), contact Virbac AH, Inc at 1-800-338-3659 or us.virbac.com. For additional information about adverse drug experience reporting for animal drugs, contact FDA at 1-888-FDA-VETS or http://www.fda.gov/reportanimalae. 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. I vermectin 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.

Storage

Store at 20°C - 25°C (68°F - 77°F), excursions permitted between 15°C - 30°C (59°F - 86°F). Protect product from light.

Other labels for this ingredient

These labels are also stored for the same active ingredient. They are not identical to the one reprinted above, and each is listed by product and set id rather than merged with it.

• HEARTGARD ® PLUS (ivermectin/pyrantel), Boehringer Ingelheim Animal Health USA Inc.. Set id 595a4883-6b37-4190-9579-a2c7ca4738eb.

FDA adverse event reports

The FDA Center for Veterinary Medicine publishes the adverse event reports it receives through openFDA. The counts below are the reports naming ivermectin and pyrantel as an active ingredient for each species this label names, as returned on 2026-09-16, coded by the VeDDRA reaction term the reporter chose. Reactions are counted per report, so one report can appear under several terms.

These are counts, not rates. Reporting is voluntary, the number of animals treated is not known, and a widely used product accumulates reports for that reason alone. A report records that an event followed a dose; it does not establish that the product caused it. The counts say nothing about how one product compares with another.