Ivermectin + Pyrantel

What is ivermectin + pyrantel?

Ivermectin + pyrantel (brand names Heartgard® Plus, Iverheart Plus®, Tri-Heart® Plus) is a combination of antiparasitic medications used to prevent heartworm and to treat and control roundworm and hookworm in dogs.

How is ivermectin + pyrantel given?

Ivermectin + pyrantel is given by mouth as a flavored chewable or chewable tablet. It may be given with or without food. If your dog vomits or seems sick after getting the medication on an empty stomach, give the next dose with food. If vomiting continues, contact your veterinarian.

This medication should take effect within one to two hours; however, effects may not be visibly noticed. Therefore, laboratory tests may need to be done to evaluate this medication’s effectiveness.

What if I miss giving a scheduled dose to my dog?

Give the missed dose as soon as you remember, and then wait the amount of time between doses recommended by your veterinarian before giving the next dose. Do not give your dog two doses at once or give extra doses.

If you are using ivermectin + pyrantel as a heartworm preventive and more than eight weeks have passed without giving this medication, contact your veterinarian for guidance.

Are there any potential side effects?

Ivermectin + pyrantel is generally well-tolerated at label doses. Contact your veterinarian if you notice any side effects such as stomach upset, vomiting, diarrhea, dilated pupils, unsteadiness when walking, or a dazed demeanor.

This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Ivermectin + pyrantel should not be used in dogs younger than six weeks of age, in dogs without a current negative heartworm test, or in dogs allergic to pyrantel, ivermectin, or similar medications, such as selamectin and moxidectin.

Some dog breeds(e.g., collies, sheepdogs, and collie or sheepdog-cross breeds) are more sensitive to ivermectin than others. This is typically due to a specific genetic mutation (MDR1) that makes them less able to tolerate high doses of ivermectin. Doses used for heartworm prevention, such as those found in the combination of ivermectin + pyrantel, are safe to use in these breeds. 

Although ivermectin is considered safe in pregnant and nursing dogs, the other drugs in this combination produce haven’t been tested in pregnant and nursing dogs.

Your veterinarian will advise you on the safety of ivermectin use in your dog.

Are there any drug interactions I should be aware of?

Some medications increase the effects of ivermectin in a pet’s brain, such as azole antifungals, cyclosporine (Atopica®), erythromycin, amlodipine besylate, and nifedipine. Interactions with pyrantel can occur with levamisole, morantel, organophosphates, and piperazine, and combined use is not recommended. Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

For dogs with potential ivermectin sensitivity, screening may be done before receiving the drug. DNA testing can determine whether a pet has the genetic mutation responsible for adverse reactions to high dose ivermectin. Ivermectin + pyrantel can be used without testing because it has a low dose of ivermectin.

How do I store ivermectin + pyrantel?

Store this combination medication at room temperature in a cool, dry place, away from heat and direct sunlight. Exposure to heat or moisture may reduce the drug’s effectiveness. Make sure your dog cannot get access to it, as, for some, the flavor is too tempting to resist eating the whole packet at once.

What should I do in case of an emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are unavailable, follow their directions in contacting an emergency facility.

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