Heartgard Plus for Dogs: Uses, Doses, and Side Effects
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PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.
Key Takeaways
- Heartgard Plus is a prescription medication for dogs that prevents heartworm disease and treats roundworms and hookworms.
- Heartgard Plus contains ivermectin and pyrantel, which target heartworms and intestinal parasites.
- Heartgard Plus is approved for dogs 6 weeks and older and is given once monthly as a chewable.
- Dogs should be tested for heartworms before starting Heartgard Plus, as it does not treat adult infections.
What Is Heartgard Plus Used for in Dogs?
Heartgard Plus is a monthly chew tablet given year-round that protects dogs from contracting heartworms, a serious parasite infection of the heart, lungs, and blood system that can cause dogs to be very sick.
Heartgard Plus also prevents and controls the two most common intestinal worms in dogs: roundworms and hookworms. These worms not only cause illness in dogs but are contagious to people.
How Does Heartgard Plus Work in Dogs?
Heartgard Plus (ivermectin/pyrantel) prevents heartworm disease and treats certain intestinal parasites.
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Ivermectin kills immature heartworm larvae (microfilariae), preventing them from developing into adult heartworms.
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Pyrantel treats and controls roundworms and hookworms by causing paralysis and death of the parasites in the intestinal tract.
How To Give Heartgard Plus to Dogs
Follow the directions on the drug label or as provided by your veterinarian.
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Give Heartgard Plus by mouth once monthly, year-round, as directed to help prevent heartworm disease and treat certain intestinal parasites.
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It may be given with or without food.
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The tablet is designed to be chewed, not swallowed whole. It can be broken into pieces or placed in a small amount of food to encourage chewing.
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After giving the dose, observe your dog for a few minutes to ensure the entire chew was consumed.
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If a full dose was not eaten, contact your veterinarian for guidance before redosing.
What Happens If You Miss a Dose of Heartgard Plus?
Speak with your veterinarian about what to do if you forget to give a dose of Heartgard Plus. Generally, your vet may instruct you to give it when you remember.
It’s important to give this medication monthly year-round, so be sure to maintain a dosing schedule every 30 days. If the interval between doses exceeds 30 days, the efficacy of ivermectin can be reduced, putting your dog at risk of contracting parasites.
Do not give extra or double doses.
What Are the Side Effects of Heartgard Plus in Dogs?
Heartgard Plus is generally well tolerated in dogs. Side effects are uncommon but may include:
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Vomiting
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Diarrhea
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Decreased energy (lethargy)
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Loss of appetite (anorexia)
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Seizures
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Loss of balance (ataxia)
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Muscle tremors
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Drooling
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Itching
If you believe your dog is experiencing any side effects, consult your veterinarian.
Human Side Effects
Heartgard Plus is a prescription veterinary medication not intended for use in humans. Due to possible side effects, humans should never use medicine dispensed for their pets and pets should not be given any medicine dispensed for a human’s use.
If you accidentally ingest a pet medication, seek medical attention in person or call Poison Control at 800-222-1222.
Monitoring Your Pet
Dogs should be tested for heartworm infection before starting Heartgard Plus. If a dog tests positive, adult heartworm treatment is required before beginning this medication.
Because Heartgard Plus kills immature heartworm larvae, dogs with an existing infection may experience a reaction after dosing. Your veterinarian may recommend additional monitoring or testing based on your dog’s health status and medical history.
When To Call Your Vet
Call your veterinarian if you see any of the following, or if you have additional questions or concerns about the use of Heartgard Plus:
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Severe side effects (above)
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Your pet’s condition worsens or does not improve with treatment
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You see or suspect an overdose
What Happens if a Dog Overdoses on Heartgard Plus?
An overdose of Heartgard may cause the following symptoms:
Most common signs:
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Vomiting
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Diarrhea
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Loss of appetite
Less common signs:
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Low energy
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Seizures
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Loss of coordination
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Muscle tremors
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Drooling
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Itching
If you suspect an overdose of Heartgard Plus, immediately seek emergency veterinary care or contact an animal poison control center. Consultation fees often apply.
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Pet Poison Helpline 855-764-7661
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ASPCA Animal Poison Control 888-426-4435
How To Store Heartgard Plus for Dogs
Keep the following storage tips in mind for this medication:
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Heartgard Plus should be stored at controlled temperatures between 68–77 F (20–25 C), with brief exposure between 59–86 F (15–30 C) permitted.
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Keep the medication in the packaging until ready for administration to protect it from moisture and light.
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Keep out of reach of children and pets.
Heartgard Plus for Dogs FAQs
Does Heartgard Plus require a prescription?
Yes, Heartgard Plus is only available by prescription from your veterinarian.
Does Heartgard Plus kill fleas or ticks?
No, Heartgard Plus does not kill fleas or ticks. It prevents heartworms, roundworms, and hookworms.
Is Heartgard Plus safe for dogs with seizures?
Yes, Heartgard Plus is considered safe for dogs with seizures. Let your veterinarian know about your dog’s seizures and work with your veterinarian to determine the most appropriate heartwormand intestinal parasite preventative plan for your dog.
What dogs should not take Heartgard Plus?
Puppies younger than 6 weeks of age should not receive Heartgard Plus. Most dogs can safely take Heartgard Plus at the recommended dose, but your veterinarian will determine whether it’sappropriate based on your dog’s age, weight, and overall health.
Can puppies take Heartgard Plus?
Yes, Heartgard Plus is approved for puppies 6 weeks and older of any weight and is given once monthly as a chewable.
Do dogs need a heartworm test before starting Heartgard Plus?
Yes, all dogs should be tested for existing heartworm infection before starting Heartgard Plus. This is because Heartgard Plus is not effective against adult worms, and infected dogs must be treated to remove adult heartworms first.
No vet writer or qualified reviewer has received any compensation from the manufacturer of the medication as part of creating this article. All content contained in this article is sourced from public sources or the manufacturer.
