Heartgard® for Dogs

Heartgard® is a monthly chewable for dogs that prevents heartworm disease. It contains ivermectin, a trusted heartworm preventive used for decades. CanadianInsulin connects you to Canadian pricing and ships to the US, helping many pet owners save without insurance.

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What Heartgard® Is and How It Works

Heartgard® is a veterinary heartworm preventive for dogs. The active ingredient, ivermectin, is a macrocyclic lactone. It kills heartworm larvae transmitted by mosquitoes before they develop into adult worms. Monthly dosing maintains protective levels as new larvae may be introduced during mosquito season.

Prevention is crucial. Adult heartworms can damage the heart, lungs, and blood vessels. Heartgard® does not treat adult heartworm infections. Dogs should have a veterinarian-performed heartworm test before starting and at regular intervals thereafter.

Who Heartgard® Is For

Heartgard® is for healthy dogs and puppies at risk of mosquito exposure. It can be used in most breeds and sizes when prescribed by a veterinarian. Puppies typically start preventive therapy when old enough, then continue monthly through the year or during the mosquito season, as advised by your veterinarian.

Dogs with a known heartworm infection need evaluation and treatment planning before preventive dosing. Use caution in dogs with a history of neurologic disease. Discuss breed-specific sensitivities with your veterinarian, especially herding breeds. At labeled doses, ivermectin is generally well tolerated.

Dosage and Usage

Follow your veterinarian’s directions and the product label. Heartgard® is given once every month. Give the chewable on the same date each month, with or without food. Ensure your dog consumes the entire dose. If needed, observe dosing to confirm full chewing and swallowing.

Typical initiation: begin preventive therapy for puppies once old enough, then dose monthly. For dogs starting later in the season, a negative heartworm test is recommended before initiation. Continue dosing during mosquito exposure and for a period after the season ends, per label and veterinary guidance.

Do not exceed the recommended dose. Do not give additional ivermectin products concurrently unless your veterinarian advises.

Strengths and Forms

Heartgard® comes as palatable chewable tablets for dogs. Weight-based sizes are commonly available. Availability may vary by market and supplier.

• For small dogs (up to 25 lb): ivermectin 68 mcg chewable tablet
• For medium dogs (26 to 50 lb): ivermectin 136 mcg chewable tablet
• For large dogs (51 to 100 lb): ivermectin 272 mcg chewable tablet

Some packs include monthly doses for several months. Your veterinarian will select the right size based on your dog’s current weight.

Missed Dose and Timing

If you miss a monthly dose, give it as soon as you remember. Then resume the regular monthly schedule. If the delay is significant, consult your veterinarian about retesting and how to proceed. Consistent monthly dosing supports continuous protection.

Storage and Travel Basics

Store Heartgard® at room temperature, away from moisture and direct sunlight. Keep in the original packaging until use. Keep out of reach of children and other pets. During travel, pack doses in a secure, dry place. Set reminders so monthly dosing stays on schedule.

Benefits

• Prevents heartworm disease when given every month
• Palatable chewable for convenient dosing
• Weight-based sizes for accurate dosing by body weight
• Veterinarian-trusted preventive with long clinical use
• Supports year-round protection in endemic areas

Side Effects and Safety

• Most dogs tolerate Heartgard® well
• Possible effects include vomiting, diarrhea, lethargy, or decreased appetite
• Occasional drooling or soft stool
• Rare neurologic signs have been reported

Serious or rare risks include ataxia, tremors, or seizures, especially with overdoses or certain sensitivities. Stop dosing and contact your veterinarian if worrisome signs develop. Dogs with MDR1 gene mutations can be sensitive to high ivermectin doses; labeled heartworm-preventive doses are generally considered safe.

Drug Interactions and Cautions

Tell your veterinarian about all medications, supplements, and preventives. Avoid duplicating therapy with other ivermectin-containing products. Use caution when combining macrocyclic lactones with products that may influence P-glycoprotein function. Discuss breed-related sensitivities and any neurologic history before starting therapy.

Dogs should be tested for heartworm infection before starting and as directed thereafter. In heartworm-positive dogs, follow your veterinarian’s treatment plan before resuming preventive dosing.

What to Expect Over Time

With monthly dosing, Heartgard® helps prevent new heartworm infections. You will not see outward changes if your dog remains healthy. Your veterinarian will recommend routine testing to confirm ongoing protection. Maintain year-round dosing in many regions or follow local veterinary guidance for seasonal use.

For broader parasite control, your veterinarian may pair heartworm prevention with flea and tick protection. For tapeworm discussions, see our guide on Droncit for Cats and Dogs.

Compare With Alternatives

Several heartworm preventives are approved for dogs. Each option differs in spectrum, formulation, and dosing schedule.

• Interceptor® Plus: a monthly chew that prevents heartworm and treats roundworms, hookworms, and tapeworms.
• Revolution® for Dog: a topical that prevents heartworm and controls fleas, certain ticks, and mites.

Your veterinarian can help select the best fit based on your dog’s needs, lifestyle, and local parasite risks.

Pricing and Access

See current Heartgard® pricing with Canadian pricing advantages and US delivery from Canada. Compare options and choose the pack size your veterinarian prescribes. Start an order online, then upload or have us confirm your prescription.

Looking for broader choices? Browse our Pet Medications category for more preventives and supplies. For general savings tips on pet meds, read Affordable Options.

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Availability and Substitutions

Availability can vary. If Heartgard® is temporarily unavailable, your veterinarian may recommend an alternative preventive. An injectable option given at the clinic is Proheart® 6, which provides six months of heartworm prevention. Your clinician will guide any changes.

Patient Suitability and Cost Saving Tips

Good candidates include healthy dogs and puppies old enough for preventive care. Dogs with confirmed heartworm infection need veterinary guidance before using any monthly product. Discuss sensitivities in herding breeds and any neurologic history.

To manage costs, consider multi-month packs when appropriate. Keep consistent monthly dosing to avoid gaps that could lead to costly treatment. Set calendar reminders or ask your clinic about refill reminders. Ordering from Canada with US shipping may reduce your pet’s medication costs over time.

Questions to Ask Your Clinician

• Is Heartgard® the right heartworm preventive for my dog?
• Should I use year-round dosing in our region?
• When should my dog be retested for heartworms?
• Can Heartgard® be combined with a flea and tick product?
• Which size and pack length fit my dog’s weight and schedule?
• Are there breed-specific precautions for my dog?
• What signs should I watch for after dosing?

Authoritative Sources

Manufacturer Website

Health Canada Drug Product Database

FDA Center for Veterinary Medicine

Ready to begin? Start your request for US delivery from Canada, and we will coordinate prescription verification with your clinic. This page is informational and does not replace veterinary advice. Always follow your veterinarian’s directions.