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Is HEARTGARD® Plus (ivermectin/pyrantel) safe?

HEARTGARD® Plus (ivermectin/pyrantel) is well tolerated. The heartworm preventive in HEARTGARD Plus chews has been trusted over 2 billion times.1 HEARTGARD Plus is the #1 vet-recommended heartworm preventive.2

Do HEARTGARD Plus chews have side effects?

In clinical field trials with HEARTGARD Plus chews, 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 HEARTGARD Plus chews: depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions, and hypersalivation. Click here for full prescribing information.


How often do I give my dog HEARTGARD Plus chews?

Give your dog a HEARTGARD Plus chew once a month, year-round.

How long does a dose of HEARTGARD Plus chews last?

Even though the dose of a HEARTGARD Plus chew only remains in the dog for a few days, each HEARTGARD Plus chew works by affecting parasitic infections acquired during the previous month/30 days.3 Therefore, it is critical to ensure that your dog receives the appropriate dose of HEARTGARD Plus each month/30 days to help stay protected from heartworm disease all year long. 

How should I give HEARTGARD Plus chews to my dog?

A HEARTGARD Plus chew can be offered to your dog by hand. Alternatively, it may be added intact to a small amount of dog food. The chew should be administered in a manner that encourages the dog to chew, rather than to swallow without chewing. Chews may be broken into pieces and fed to dogs that normally swallow treats whole. Care should be taken that your 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.3

Talk to a vet about the right way to protect your dog from heartworm disease.


How does HEARTGARD® Plus (ivermectin/pyrantel) work?

HEARTGARD® Plus (ivermectin/pyrantel) contains 2 active ingredients, ivermectin and pyrantel. The ivermectin works to prevent heartworm disease by allowing the immune system to recognize and inactivate heartworm larvae before they can develop into adults.4 The pyrantel in HEARTGARD Plus chews treats and controls hookworms and roundworms.4

Does my dog need a prescription for HEARTGARD Plus chews?

Your dog will need an annual negative heartworm test and a prescription for HEARTGARD Plus chews from your licensed veterinarian.

Is there a weight or age requirement to give my dog HEARTGARD Plus chews?

HEARTGARD Plus chews are suitable for dogs 6 weeks of age and older. There is no minimum weight requirement to use HEARTGARD Plus.3

Do HEARTGARD Plus chews need to be used all year even when it is cold outside?

The American Heartworm Society recommends giving your dog year-round protection.5 That’s because the threat of heartworm disease doesn’t stop with dropping temperatures. Many pet owners might assume that they only need to give their dog heartworm disease preventives when it’s warm. While heartworm transmission can decrease in winter months, the risk never reaches zero. What’s more, on-again, off-again heartworm disease protection is unreliable and can leave gaps in protection that can make your dog vulnerable to heartworm disease.

In what sizes and options are HEARTGARD Plus chews available?

HEARTGARD Plus chews are available in 3 different sizes: for small dogs up to 25 pounds, medium dogs weighing 26-50 pounds, and large dogs weighing 51-100 pounds. For dogs over 100 pounds, use the appropriate combination of these chewables.3 Each size also comes in packs containing 1-, 6-, or 12-month doses. HEARTGARD Plus is safe to use in all dogs aged 6 weeks and older. Following the use of HEARTGARD Plus, digestive and neurologic side effects have been reported.


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Do HEARTGARD Plus chews only prevent heartworm disease?

No, the pyrantel in HEARTGARD Plus chews treats and controls hookworms and roundworms.4

Who can I speak with regarding any specific HEARTGARD Plus chews questions?

For any specific product questions, please talk to your vet or call the customer service line of Boehringer Ingelheim Animal Health at 1-888-637-4251.

What is heartworm disease?

Heartworm disease is an invisible, but potentially fatal threat that occurs in dogs and other animals. Heartworms (Dirofilaria immitis) are parasitic worms that are transmitted to dogs by infected mosquitoes. Microscopic larvae of heartworms develop and grow under the skin, then migrate to the blood vessels of the heart and lungs of the infected animal where they rapidly grow, becoming adults that are 5-12 inches in length.5

How do dogs get heartworms?

Dogs get heartworms by being bitten by an infected mosquito. Larvae are deposited on the skin when the infected mosquito bites, then when the infected mosquito leaves, the heartworm larvae enter through the bite wound. One bite is all it takes.6

What are the signs of advanced heartworm disease?

Not all dogs develop noticeable clinical signs. While blood tests performed by your veterinarian are the only way to confirm a diagnosis of heartworm disease in dogs, here are 5 warning signs that are reported in dogs with advanced heartworm disease: 


1. A persistent, dry cough is a common sign seen in dogs with advanced heartworm disease.


2. Lethargy and reluctance to exercise are also common signs described in dogs with heartworm disease.


3. Some dogs have a decreased appetite and, as a result, lose weight.


4. As heartworm disease progresses, it can lead to heart failure. You may notice that your dog’s belly appears swollen from fluid in the abdomen.


5. In the most advanced cases, dogs can develop more severe respiratory issues like rapid breathing in addition to coughing.

How can I reduce the risk of heartworm disease in my dog?

There are 3 things you can do to help reduce the risk of heartworm disease:


1. Use monthly preventives, like HEARTGARD Plus chews, on a year-round basis to safely and effectively prevent heartworm disease by affecting the heartworm larvae before they can grow into dangerous adult heartworms.4


2. Reduce mosquito exposure by eliminating standing water where mosquitoes can breed, avoid known mosquito habitats, and limit outdoor exposure during peak mosquito feeding times.5


3. Get your dog tested every year. Before getting a prescription for a heartworm disease preventive, your dog must be tested for heartworms. Talk to your vet about testing options.5

Can heartworm disease be treated?

Yes, it can be treated, but heartworm disease is a serious condition that can cause heart failure, permanent damage to your pet’s lungs, and even death.4 Treating heartworm disease is costly and complicated.7

How do dogs get hookworms and roundworms?

Hookworm larvae can be transmitted through the skin or by ingesting larvae in contaminated soil or grass at places like the dog park. Roundworm larvae can be transmitted through a mother’s milk or by ingesting infective eggs from the soil in your backyard.8

What is the vet-recommended way to protect my dog from heartworm disease, hookworms, and roundworms?

The vet-recommended way to protect your dog is by giving them a broad-spectrum heartworm disease preventive like HEARTGARD Plus chews that also kills hookworms and roundworms every month.