Heartgard Chewable Tablets for Cats, up to 5 lbs, 6 treatments

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Your furry friend must have a current heartworm test result on file with your veterinarian in order to be prescribed heartworm medication. Please visit your veterinarian to have this test performed annually to protect your four-legged friend. Heartgard is a heartworm preventative that kills feline heartworms and helps to control and treat hookworms. Given monthly, it comes in a chewable tablet that you can feed to your pal as a tasty, beef-flavored treat. If your cat has a tendency to swallow her food or treats whole, you can break each tablet into small pieces for easier feeding.


To prevent heartworm disease by eliminating the tissue stage of heartworm larvae Dirofilaria immitis for a month (30 days) after infection and for removal and control of adult and immature hookworms Ancylostoma tubaeforme and A. braziliense.

Possible Side Effects

Please contact your veterinarian if the following adverse reactions occur: depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions, and hypersalivation.

Drug & Food Interactions

Talk to your veterinarian about any other drugs your pet is taking before starting this medication.


It is recommended that pets should be tested for existing heartworm infection prior to starting treatment with this medication. 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.

  1. Prescribing Information

See all items by Heartgard

  • Item Number
  • Dosage Measure

    Use according to your veterinarian's instructions.

  • Generic Name


  • Common Brand Name(s)

    Heartgard, Ivomec

  • For Use With

    Cats - 6 weeks or older

  • Brand

    Merial, Boehringer Ingelheim

  • Product Form

    Chewable Tablet

  • Health Condition

    Heartworms, Hookworms

  • Drug Type




Recommended Dosage

Consult your veterinarian for proper dosing instructions. For use in pets six weeks of age and older. Administer once a month. The initial dose must be given within a month after pet’s first exposure to mosquitoes. The final dose must be given within a month after the pet’s last exposure to mosquitoes.

Storage Instructions

Heartgard Chewables for Cats are stable for 3 years when stored below 77°F and protected from light.

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. The recommended dosage schedule for prevention of feline heartworm disease and control of hookworm is as follows:

Cat Weight HEARTGARD for Cats per Month Ivermectin content
Up to 5 lbs 1 chewable 55 mcg
5 to 15 lbs 1 chewable 165 mcg

For cats over 15 lbs, use the appropriate combination of chewables. HEARTGARD for Cats is recommended for use in cats 6 weeks of age and older.


What is heartworm disease?

Heartworm disease in cats (dirofilariasis) is a serious and potentially fatal disease. Heartworms spend their adult lives in the pulmonary arteries. The adult worms can cause lasting damage to the heart, lungs and arteries.

How do cats get heartworms?

Heartworms are transmitted from one cat to another by mosquitoes, which pick up tiny immature heartworms, called microfilariae, when they bite an infected cat. Larvae develop and are then transmitted to another cat when that cat is bitten by the infected mosquito.

Where are cats at risk for heartworm infection?

All cats are at risk for heartworm disease, no matter where they live—heartworms don't discriminate based on geography. In the past, heartworm disease in the United States was primarily limited to the South and Southeast regions. However, it is now found in all 50 states, in Canada, and is spreading to new areas each year. The American Heartworm Society notes that uncared-for cats and certain wildlife can be carriers of heartworms. Mosquitoes blown great distances by the wind and the transportation of infected pets to different geographic locations can all contribute to the spread of heartworm disease.

What are the signs of heartworm infection?

Signs of heartworm disease can be subtle and difficult to detect until its later stages. As the disease progresses, signs begin to appear. Contact your veterinarian immediately if you notice coughing, difficulty breathing, sluggishness and less energy for exercise in your cat. Adult heartworms cause serious harm to your cat's heart, lungs and certain internal organs. Left untreated, heartworm disease can result in loss of consciousness and death.

How are cats tested for heartworm infection?

The most common method for heartworm testing is for a veterinarian to collect a small blood sample from a cat and evaluate the sample using a specialized test kit to detect the presence of adult heartworms.

How can heartworm disease in cats be prevented?

Pet owners can use Heartgard (ivermectin) to help prevent heartworm disease. Heartgard kills tissue larval stages of heartworms and helps prevent them from developing into adults and causing heartworm disease. In an unprotected cat, heartworm larvae mature into adults and ultimately migrate to the arteries of the lungs.

How long do I have to give my cat Heartgard?

Monthly use of Heartgard is essential because it cannot be determined with certainty when the threat of mosquitoes has passed. Talk to your veterinarian for dose and regimen recommendations.

Can heartworm disease be treated?

Although it is possible to treat heartworm disease if a cat becomes infected, it is difficult, expensive and risky, particularly in cats that have begun to exhibit clinical signs of infection.

What if my cat becomes infected with heartworms?

There are treatment options available to kill adult heartworms in cats that have become infected. Treating cats with heartworm disease starts with a thorough physical examination by the veterinarian. The veterinarian will then discuss treatment options with you. Typically, the cat is hospitalized during the treatment period. Because there is a risk of blood clots or worm debris blocking blood vessels from adult heartworm treatment, the cat must then remain quiet in close confinement for another 4 to 6 weeks after treatment. A second round of treatment may be required for some cats. The veterinarian may also give your cat a treatment to rid it of the immature larvae that are circulating through the blood stream.

Is Heartgard safe to use in any breed of cat?

Heartgard is safe and effective in any breed of cat when used as directed.

Can my cat "get" heartworm disease directly from an infected cat?

No, the way cats become infected is via a bite from a mosquito that is carrying heartworm larvae.

Are nursing kittens immune to heartworm disease if the mother is receiving Heartgard?

No. kittens that are nursing may become infected. Heartgard can be used in kittens as young as 6 weeks of age—and kittens benefit from the ability of Heartgard to treat and control roundworms and hookworms.

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