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Accidentally Gave My Dog 2 Doses of Heartgard – Should You Be Worried?

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You might wonder how is it possible accidentally to give your dog 2 doses of Heartgard?

There could have been multiple reasons for this mishap. One of the likely causes is that you might have misread the instructions on the package and given your dog two doses instead of one without first consulting your dog’s veterinarian. Yet another possibility is that the medication got mixed up, and in confusion, you accidentally ended up repeating the dose, making it two instead of one.

It is very easy to make a mistake like this, so be sure to take your time and double-check the dosage before you give it to your pet.

To err is to human,” and we all make mistakes every now and then. It doesn’t mean we love our pets any lesser. Honestly, the composition of Heartgard is such that it won’t even make much of a difference in case you have doubled the dose. However, it is neither recommended nor encouraged to give more than the prescribed dosage of any medicine. Hence, it is always better to be safe than sorry. If you have mistakenly doubled the dose of Heartgard, it is best to call your vet and seek professional advice.

What is Heartworm?

What is Heartworm

Heartworm disease is an infection caused by a worm parasite that can have fatal consequences. It is known to be transmitted by mosquitoes. Mosquitoes are known to carry the heartworm larvae from one animal to another. If you were offering Heartgard medications to your dog, you are probably aware of the disease and its consequences.

So, now you know about the disease, let us know more about how this disease can i mpact your pet’s health, and how Heartgard is the right medicine prescribed by your dog’s vet to ensure a speedy recovery.

What Symptoms to Look Out For Heartgard Overdose in Dogs?

Overdose of Heartgard may have serious health repercussions on your dog. The symptoms can be mild and non-alarming. And if your pet dog is suffering from vomiting and diarrhea, there can be other symptoms that may follow. Some of them are:

1. Loss of Appetite

Vomiting can make your dog weak, and in the long run, your canine friend may suffer from loss of appetite. They may refuse their favorite treat and sleep throughout the day. So, please look out if your dog is avoiding meals.

2. Lethargy

Lack of proper nutrition may make your furry friends weaker, and they may become lethargic. They may not like to move from their resting position, keep yawning, and sleep throughout the day. So, an unusual lazy dog implies that she/he has been administered with an overdose of Heartgard.

3. Excessive Drooling

Drooling is one of the most common features among dogs, even in general. But if your dog is drooling too much, especially after being administered Heartgard, please be cautious. This may indicate that the amount of Heartgard it has consumed is more than the prescribed quantity.

4. Seizures

One of the most severe symptoms of an overdose of Heartgard is violent fits or frequent episodes of seizures. This is a symptom that is easy to observe since most dogs do not suffer from seizures under normal circumstances. So, if you find your pet having seizures after consuming Heartgard, immediately contact your veterinarian.

5. Skin Irritation

Skin irritation is another symptom of an overdose of Heartgard, and if you find your dog to be frequently using its paws to scratch itself all over, you probably have fed your pet buddy more Heartgard than you should have.

6. Blood in the Stool

This symptom is a serious one and is easy to detect. The moment you find blood in your dog’s stool, especially after being administered with Heartgard, immediately take your pet to the doctor and follow up on the required procedure.

7. Change in Behavior

Overdose of Heartgard may lead to erratic and irrational behavior in your dog. They may act weird and become aggressive. So, any erratic behavior like unnecessary biting is an indication your dog is suffering from an overdose of Heartgard.

Benefits of Using Heartgard

Benefits of Using Heartgard

Now that you have known the repercussions caused due to an overdose of Heartgard, that should not be a reason to dissuade you from administering your dog with Heartgard.

Prevention of Heartworm Disease

Heartgard works by killing heartworm larvae that are present in the dog’s bloodstream.

Reduced Risk of Other Diseases Caused by Heartworm Infection

Heartworm infection can cause a variety of problems in pets, ranging from respiratory to neurological. Early diagnosis and treatment are essential for the best possible outcome for your pet.

Easy to Administer

Most veterinarians administer Heartgard to dogs at an early stage to ensure that the infection subsides as soon as possible.

Convenient Once-a-month Chewable Tablet

Heartgard should be given to dogs once a month, and it is best to provide it at a particular date in a month. As the tablets are chewable, people mistakenly give two doses to their dog.

How Much is Too Much Heartgard For Dogs?

Heartgard contains ivermectin and pyrantel. The minimum dosage of this salt combines 2.72 mcg/lb and 2.27mg/lb. Since this combination is strong, administering Heartgard is not favored if your puppy is less than six weeks old. Therefore, it should be administered according to the weight of your dog. Also, if you have a big dog weighing over 100 lb, there are chewable tablets of Heartgard in the market.

Ideally, if your dog weighs up to 25 lb, a 68 mcg of Ivermectin content and 57 mg of Pyrantel content should suffice. If your dog weighs anywhere between 26 lb to 50 lv, 136 mcg of Ivermectin content and 114 mg of Pyrantel content is required. For dogs weighing anywhere between 51 lb to 100 lb: the prescribed dosage of Ivermectin and Pyrantel content is 272 mcg and 227 mg, respectively.

Can I Give My Dog A Higher Dose Of Heartgard?

Dogs with heartworm disease need to be treated carefully. As a pet parent, you should know the proper dosage of Heartgard and what works for them the best.

Many dog owners suffer from this problem because they might need to be aware of the safety of a certain amount of Heartgard for their dogs. Therefore, it is best to inquire about the dosage of Heartgard that can be safely administered to dogs.

Heartworm is a parasitic that can be carried to dogs by the bite of an infected mosquito. One of the simple measures against heartworm illness is administering Heartgard.

Meanwhile, Heartgard is a drug that your veterinarian may advise you to give to your dog in order to assist in avoiding heartworm disease.

The solution largely relies on your dog’s size and body weight when you’re worried about administering a higher dose of Heartgard. Delivering the suggested quantity is generally preferable, rather than providing a lesser or greater dose.

Let us quickly look at the amount of Heartgard that can be given to dogs without posing any serious risk.

Recommendation Of Heart Gard For Different Dogs Of Different Sizes And Bodyweight

As previously noted, your dog’s size and body weight play a critical role in determining the appropriate Heartgard medication. 

Heart Gard pills are available in various sizes and can be given to big, medium, and small-sized dogs, depending on their weight. However, the quantity needs to be increased based on your dog’s size.

Is It Right To Give More Than The Recommended Amount?

You may not be entirely right when you believe that administering more Heartgard will enhance the likelihood that your pet won’t contract heartworm disease. First, administering a higher dose will not increase its effectiveness.

Moreover, it is equally important to question if Heartgard has any adverse effects on your dog’s health. Well, it does, similar to a variety of prescription medications.

If you choose to administer a higher quantity of Heartgard, let us tell you that a greater dose may result in even more difficulties than normal.

Depending on your dog’s weight fluctuations and how they respond to the medication, you might occasionally need to administer greater quantities. 

So it would be best to avoid administering a larger amount of Heartgard. However, there are some additional factors to be considered as well.

Besides, raise it continually based on how the dog responds to the recommended dosage of Heartgard. Because it is created exclusively for dogs, it takes a significant dose to have negative impacts.

Before providing Heartgard to a dog to cure heartworms, a veterinarian should indeed be consulted.

Can I Give My Dog A Lower Dose Of Heartgard?

Dogs are treated with Heartgard to combat heartworm infection. This is an oral drug that is used every month. Heartgard has the advantage of being simple to administer to dogs. Besides, it is considered successful at treating heartworm infections.

The medicine is prescribed at a measured rate for each dog, keeping its size and body weight in mind. Some canines, nevertheless, might be capable of withstanding a lesser amount.

Remember that Heartgard works against a parasitic worm that causes infection in a dog through the bite of a female mosquito that is infected. 

The medication depends entirely on the dog’s body weight and physique. If a dog’s weight is less, the amount of medication is less; if more, the quantity will be more.

Is It All Right To Give A Lower Dose Of Heart Gard?

Yes, Heartgard could be administered to certain dogs at a more minor concentration. But tampering with the prescribed amount of medicine is not at all recommended. 

Yet, some dogs may be able to withstand such changes in concentration while others will not be able to tolerate the same.

Moreover, consult your vet first if you are thinking of administering a lesser quantity of Heartgard. They will indeed be able to instruct you on the safety of the medication for your dog and the recommended dosage.

As you already know, the most effective way to prevent heartworms in your dog is with Heartgard. Nevertheless, dog owners remain hesitant to administer this medication to their dogs if they don’t fully comprehend it.

Given that it might have minimal adverse effects, they will most likely give a lower dose. At the same time, sometimes, some dog owners purchase smaller doses.

You should know that dogs are divided into three weight groups. The first one is small-sized, the second one is medium-sized, and the last one is large-sized.

Each group has a specific amount of medication. So, when you give your dog a smaller dose than advised, it’s not always the best course of action.

Furthermore, veterinarians say it’s critical to administer a precise amount of Heartgard based on your dog’s size. A lesser dose won’t benefit the dog at all; rather, this can also lessen the medication’s effectiveness.

In the end, it might not be able to eradicate the contamination of heartworm completely. This, in turn, jeopardizes the whole purpose of the medicine.

What Should I Do If I Can’t Remember If I Gave My Dog Heartworm Medicine?

First of all, relax! A medicine like Heartgard is meant to help your pet fight a deadly disease, and the way it works is by killing the worms attacking your pet. The treatment will take time to work, and if you can’t recall if you gave your dog the medicine, you can administer another dose just to be sure.

You can use a few tricks to ensure that you remember to give your pet the medicine next time.


Mark your calendar based on the prescription. You can also set reminders on your phone to ensure that you do not miss the day or time when the medication is due.

Mix in Food

If your dog is acting up about taking medicine and is reluctant to follow instructions, you can mix the medicinal drugs in their food to ensure there is no trace of medicine.

Pill Case

Another efficient way is to maintain a pill case. The probability of forgetting to give your dog the required Heartgard dose is significantly reduced when you have a pill case. This is because you will have to open the case and take out the pill every time you need to give it to your dog.

Is It Dangerous If I Give My Dog A Heartworm Pill Early?

Puppies who contract heartworm infections may experience severe and long-lasting consequences. To begin, Heartworms cause abnormalities in the puppy’s cardiovascular system quite early. Your puppies’ cardiovascular system can be weakened even before anything can be noticed.

To make matters worse, vascular swelling in the cardiovascular system is brought on by heartworms. Moreover, the liver and cardiac muscle alone can do heavy damage. 

Unfortunately, when you delay appropriate treatment and the required medication until your puppy exhibits heartworm clinical signs, medication will be significantly difficult, risky, or perhaps hopeless.

By the time the heartworm contamination is discovered and properly treated, harm to the liver, heart muscle, kidneys, and vessels in the lungs may already be done. This implies that your puppy can experience a decreased survival rate due to their heartworm disease.

Can Heartgard Be Administered Early?

Heartworm illness is a terrible health condition and can be fatal for your dog, especially young puppies. It can even cause the death of your cherished pet. Therefore, prevention is crucial in this case! We recommend you not waste time on home remedies and take your pet to the doctor.

You are probably wondering now what will happen in case you have to leave on tour for work or another reason, thereby making it impossible for you to remain at home and administer your dog the medication on time. 

Do you want to skip administering Heartgard while you are away? Or is it acceptable to deliver it before the specified date?

Let us warn you immediately that one of the most hazardous aspects is delaying or skipping the heartworm medication, so take that into account. 

If such an event occurs, heartworm larvae will grow into adults and become adult heartworms, which is what these preventative medications will not be able to halt.

Now, if we come to the previously mentioned question, the answer can be given in two views.

In case of a mild condition

If you are wondering about the possibility of beginning to administer heartworm medication when the condition is still mild, the answer is YES. 

Heartworms survive and reproduce within adult canines, which serve as their hosts. Therefore, they have a negative impact on your dog’s health and can injure the heart, lungs, and vessels.

Therefore, it’s advisable to begin the therapy as promptly as possible. Doing so will result in your dog’s life being saved. However, remember that any medication on your dog must first be evaluated.

Administering the pill before the 30 days cycle

There are some pet owners who have already started administering heartworm treatment and are still determining if they can administer a pill sooner than the recommended 30-day period. In this case, the reply is, once more, a YES.

However, there is a crucial aspect that you need to keep in mind. The rotation of medications should now be restarted, albeit there is no danger in providing it early. This is because the new cycle you receive now corresponds to the new time each month to administer heartworm medication.

Your dog’s system typically retains heartworm medication for 24 to 48 hours. Within this time frame, young larvae will be killed. The medication will then be eliminated from the system.


What if I accidentally gave my dog 2 heartworm pills?

You might be surprised to learn that two heartworm pills will not cause much of a worrisome impact on your dog’s health.

When your dog consumes two doses of Heartgard, the only thing that might reasonably occur is a brief episode of a stomach problem like loose motion.

Yet, if you notice some change in a dog’s behavior, we recommend you take it to a vet.

What are the active ingredients in Heartgard?

The active ingredients in Heartgard are ivermectin and pyrantel pamoate.

What are the dosages for Heartgard?

The dosages for Heartgard vary depending on the weight of the dog. The recommended dosage is 0.5 mg/kg of body weight, given as a single dose each month.

What happens if I give my dog an extra Heartgard?

You need not worry much if you give your dog an extra Heartgard. The composition of Heartgard is maintained in such a way that even 4-5 doses of Heartgard will not create a great deal for your dog’s health.

Yet it is neither recommended nor will it be safe. To begin, it can lead to vomiting or diarrhea among dogs. Moreover, if you think that your pet feels agitated, take it to a vet.

Can you overdose on heartworm medication?

It is never recommended to overdose any medication on any animal. So, make sure that the medication for heartworm is given according to the prescribed amount.

In case you want to give a greater amount of doses, then administer it in a gradually increasing manner. It is still better to contact a vet before doing the same.

What happens if my dog eats 2 NexGard?

NexGard is nothing but another type of medication that works just like Heartgard. It is commonly used to treat infections caused by worms. When a dog takes or swallows many doses of NexGard, there is a significant risk of harm.

Besides, if given two times the maximum amount, healthy dogs with proper body weight generally show no negative side effects. However, vomiting and diarrhea can be noted at roughly a 5-fold overdose.

How long does HEARTGARD Plus stay in the dog’s system?

Generally, pills like Heartgard Plus stay around 24 hours within the dog’s system. The effects of these medications remain for the next 30 days, and they are given monthly for a particular period. The dose can sometimes remain in the dog’s system for at most four days.

Can you give Heartgard early?

Yes, Heartgard can be given early. In fact, pups as little as six and eight weeks old can start taking this medicine to combat heartworm. Before receiving routine care, it’s indeed crucial for your dog to get a heartworm diagnosis if she is a bit older than six months.

Please remember that a pup remains at risk of contracting heartworm from the first day of its life.

How quickly does Heartgard take effect?

Yes, Heartgard can be given early. In fact, pups as little as six and eight weeks old can start taking this medicine to combat heartworm. Before receiving routine care, it’s indeed crucial for your dog to get a heartworm diagnosis if she is a bit older than six months.

Please remember that a pup remains at risk of contracting heartworm from the first day of its life.

How quickly does Heartgard take effect?

Heartgard acts on a dog’s system really quickly. It starts working as soon as it enters a dog’s circulation and mixes with the blood. All it needs is to be adequately swallowed and then absorbed within the body.

Final Verdict

We all want to do our best to ensure the well-being of our pets. There can be a few errors in our judgment every now and then. Honestly, Heartgard has more benefits than drawbacks. You can always check with your vet in case something goes wrong. Quick treatment can prevent health issues. Yet prevention is always better than cure.

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