Using Tri-Heart Plus vs. Heartgard for Dogs Which Preventative Is Right for You and Your Dog?

Using Tri-Heart Plus vs. Heartgard for Dogs
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Tri-Heart Plus

Heartworm & Deworming
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Let's face it, worms are icky whether they are outside or inside your pet. However, if these parasites get inside, they can cause great harm to both your pet's heart and gastrointestinal tract. Learn more here are about these two preventatives, Tri-Heart Plus and Heartgard for Dogs, so you can best protect your dog from intestinal parasites.

Most dog owners know: that worms can be a serious threat to the health and well-being of our beloved pets. To get ahead of these nasty pests, dog owners should use a bit of preventative heartworm medicine for dogs. Below are descriptions and comparisons of two effective heartworm and internal parasite medicationsTri-Heart Plus vs. Heartgard.

What Types of Pests Do Tri-Heart Plus and Heartgard Kill?

Tri-Heart Plus and Heartgard are both oral medications that are effective at preventing heartworms in dogs.

  • Heartworm pills for dogs like Heartgard protect against heartworms alone.

  • Tri-Heart Plus, as its name implies, protects against three types of parasites: heartwormroundworm, and hookworm.

  • Both of these medications are effective in heartworm prevention for dogs and should not be given to your pet if worms are already present.

  • Heartworm meds for dogs target internal parasites but do not guard against other pests like fleas or mites.

How Long Does a Dose Last?

Both Tri-Heart Plus and Heartgard are formulated to last for 30 days. They’re both tasty enough that your dogs should eat them readily each month.

Should My Pet be Kept Inside or Alone After the Dose?

Tri-Heart Plus and Heartgard are oral medications, so you will not need to quarantine your dog or keep your dog inside after administration, as you might have to with spot-on parasite preventatives.

The first thing you need to consider when setting up a quarantine is whether or not it's necessary. Sometimes "quarantine" can be used as a catch-all term for separation from other animals without considering if there's actually any risk of disease transmission. If your dog has been around other dogs but hasn't shown any signs of illness, there's probably no reason to place them in isolation.

The second thing you need to consider is why you're quarantining your dog in the first place. Is it because they've been exposed to an unknown pathogen? Are they showing symptoms of illness? Is there a potential health risk for others if they're not separated from their usual environment? These are all important factors that will help determine how long your dog should be kept away from other pets or people.

If you have multiple pets, give your quarantine dog separate dog bowls, keep them in separate dog cages, and also separate their dog chew toys. You wouldn’t want the disease to spread (if your dog has it in the first place).  

Are There Any Side Effects?

Both Tri-Heart and Heartgard contain ivermectin. Tri-Heart contains pyrantel as well. These drugs are toxic, and although their intended target is parasites, they can have an effect on your pet’s well-being as well.

Common side effects include diarrheavomitinganorexiadepression or lethargy, mydriasis, ataxia, staggering, excess salivation, and convulsions. If any of these side effects present themselves while your dog is taking these medications, contact your veterinarian immediately.

Be sure your dog does not already have a full-stage worm infestation before beginning preventative treatment with these chewable medications. These drugs are for the prevention of parasites, not treatment of an existing infestation.

Collies and other herding dogs are especially sensitive to ivermectin. You should discuss alternative options with your veterinarian.

There are a number of reasons why dog medications have side effects.

First, the dosage is often adjusted based on the dog's weight and age, which means that there may be more or less of a certain ingredient in each pill. This means that one dog could react differently to an ingredient than another.

Secondly, the ingredients used in each medication vary from one manufacturer to another. A dog might react negatively to an ingredient in one brand but not another brand because the two manufacturers use different sources for their ingredients.

Thirdly, some dogs may simply be allergic to certain ingredients in their medications.

My Pet is Only a Few Weeks Old. Can I Use Tri-Heart Plus or Heartgard Safely?

Tri-Heart and Heartgard are both intended for use with puppies that are at least 6 weeks of age. 

My Pet is Pregnant Or Nursing. Can I Still Use One of These Medications?

Both Heartgard and Tri-Heart are safe for pregnant female dogs, as well as for both male and female dogs that are to be used for breeding.

Both of these medications are available from your veterinarian by prescription only, so talk to them about using these drugs with your pregnant or breeding dogs.

If you’re still concerned, use the Seresto Flea Collar for Dogs to keep mosquitoes away. By keeping mosquitoes away, this dog collar will prevent your pregnant or nursing dog from getting heartworms and other diseases.

Pregnant dogs must be fed a balanced diet. This means that the amount of protein, fat, and carbohydrates in their food should be roughly equal. It's also important that pregnant dogs get all of their nutrients from food and not from supplements or vitamins. This will ensure that the puppies are getting everything they need to grow and develop properly.

If your dog is pregnant, it's important to keep an eye out for any changes in her behavior or personality. If she suddenly starts acting differently than she normally does, this could be a sign that something is wrong with her pregnancy, and you should take her to see your veterinarian right away.

How Does Tri-Heart Plus and Heartgard Work?

Ivermectin and pyrantel, the active ingredients in the Heartgard and Tri-Heart Plus medications, work in similar ways.

Ivermectin targets heartworms and causes paralysis in heartworms in the larval stage. Affected worms are unable to travel toward the dog’s heart, and so they die, unable to reach adulthood.

Pyrantel is a neuromuscular blocker. It, too, causes paralysis -- in roundworms and hookworms. When they become paralyzed, they lose their grip on the dog’s intestines and are passed into the dog’s stool.

Heartgard and Tri-Heart come in four dosage sizes that are administered to your dog based on their weight.



Pests controlled

 Recommended age of application


 Oral; 1-month dose by chewable tablet

 Larval heartworms

 6 weeks and older

 Tri-Heart Plus

 Oral; 1-month dose by chewable tablet

 Larval heartworms, intestinal round, and hookworms

 6 weeks and older

More on Worms In Dogs

How Testing for Heartworm Changes with Lifecycle
Is Your Dog Eating Poop?
Can People Get Heartworms?

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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