Heartgard vs. Sentinel Heartworm Treatment for Dogs & Cats : 2024 Comparison

Heartworms can cause a lot of suffering for your pet, so you definitely need to have a plan for prevention. If you aren’t already giving your pet heartworm medication, it’s time to make some critical decisions.

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Don’t think your indoor pet is safe either. Indoor pets can still come down with a heartworm diagnosis, so your pet should be on some sort of preventative regardless of the amount of time your pet spends outside.

Two excellent examples of heartworm prevention are Heartgard and Sentinel. Heartgard is straightforward and more well known. Sentinel is more comprehensive, but it can be more expensive. They come in chewable form to make it easy to administer, and both cover more than just heartworms. So which one is the right one for you?

We’ll break down everything to help you decide which one might be the best pet prescription for heartworms. You need to know about the ingredients and dosages, plus how convenient they are to give to your pet. We’ve made our decision. Let’s get you up to speed.

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Which is Better Heartgard or Sentinel for Dogs?

Heartgard is generally better for dogs except for a few instances. The main ingredient in Heartgard has been shown to affect some collies adversely, so you’ll want to talk to your veterinarian before beginning that treatment.

Heartgard won’t control whipworms or flea infestations either. Sentinel covers both of those things. If you’ve already got a flea treatment you like, Sentinel may be a bit of overkill. We tend to prefer simpler treatments, but if you’ve got a collie or you’d want to have a single treatment for internal and external parasites, Heartgard should do the trick. It’ll also be easier on your wallet.

Which is Better Heartgard or Sentinel for Cats?

Sentinel isn’t approved for use in cats, so you’ll definitely want to stick to Heartgard on this one. Heartgard can help with feline heartworms, a condition that’s just now being understood and diagnosed.

The good news is that Heartgard is prescriptible much sooner than Sentinel anyway, so young cats can begin treatment much earlier with Heartgard than they could with Sentinel (even if they could use it).

Heartgard comes in two different versions. It’s essential for you to give your cat the version of Heartgard made specifically for cats. The two are not interchangeable, so be sure you get the right version for your cat or your dog.

Our Review of Heartgard and Sentinel

Both Heartgard and Sentinel come in easy chewable tablets. They’re beef flavored and intended to act as a treat for your pets. They eat the medicine and are good for the month.

Both require a prescription, and you should talk to your veterinarian before you start any sort of regimen for your pet. However, let’s break down what each medicine is about.

Key Differences Between Heartgard and Sentinel

There are a few things that distinguish these two.

Other Pests

Heartgard does protect against some other types of worm infestations, such as roundworms and hookworms. It doesn’t offer any protection against things like fleas or ticks. One of the downsides for Heartgard is having to use multiple treatments to protect against inner and outer pests.

Sentinel protects against a more extensive variety of pests. It protects against roundworms and hookworms like Heartgard, but it also protects against whipworms. It also interrupts the life cycle of the flea. If your pet isn’t already on flea medication, it can remove one step in your prevention plan.

Dogs And Cats

Both options are suitable for dogs, but cats don’t have a Sentinel version. You’ll need to give them Heartgard only. Make sure you use dosages specific for cats. If you have both cats and dogs in your household, be sure not to mix their treatments or buy the same box for both.

Heartgard doesn’t cover all pests so your cats will also need to be on a flea treatment of some kind. If you’re already using a flea treatment that you like, Heartgard could be a suitable addition.


Sentinel can be administered to dogs starting at eight weeks of age. With Heartgard, you get an extra two weeks head start with 6 weeks. If you’ve got a really young dog, you may need to begin with Heartgard anyway for that extra protection.

Pregnant And Nursing Pets

Heartgard is considered to be safe for pregnant and nursing animals, so you could still continue your treatment even if something happens.

Sentinel isn’t safe, or the effects aren’t agreed upon. If your pet becomes pregnant, you’ll have to switch to some other treatment.

Read our article about: Simparica vs. Bravecto

Heartgard and Sentinel Active Ingredients Comparison

Sentinel: Milbemycin Oxime and Lufenuron

Milbemycin Oxime is a neurotoxin that interferes with the neurotransmitters of worms. It controls the population and prevents their breeding cycle. They die off, and your pet is worm free. Lufenuron also works on the larval stage of worms and insects. That also helps prevent flea infestations through the same type of neurotoxins. It won’t treat adult fleas, but it can prevent any eggs from hatching and larva from proceeding to adulthood.

Work with your veterinarian to make sure that your pet is getting the right dosage because these ingredients can be very difficult for dogs if they aren’t getting the right amount. Look for issues with digestion and skin.

Heartgard: Ivermectin

Ivermectin is another neurotoxin that acts on worms by interrupting neurotransmitters and causing death. Heartgard is only approved for dogs. Cats will need the dosage formulated explicitly for them so be sure not to mix the two.

Be sure that you pay close attention to the dosage because overdosing on Ivermectin can be very dangerous for your pet. Work very closely with your vet to make sure that your pet is getting the correct dosage.

Which Treatment is the Best Priced?

Heartgard is cheaper, but you have to remember that Sentinel is more comprehensive. You’ll get a flea treatment as well as a treatment for whipworms. Since you wouldn’t have to have a separate treatment for those things, it may be more economical to go with Sentinel.

If you don’t need those things, Sentinel may be overkill for your pet. The cost for Sentinel may not be necessary at all if you don’t need expanded treatments.

Both get more economical the more doses you buy at once, so you could consider stocking up. You could also get a discount for automatic shipments that could bring the price to something closer in range to your budget.

Which Do We Recommend?

We recommend the simplicity of Heartgard overall. It’s cheaper and for many pets, tastier. We do favor medications that are simpler, and for that, Heartgard has you covered. It’s also considered safe to administer to pregnant or nursing pets.

You can begin treatments two weeks earlier with Heartgard, which makes it better for those getting a puppy. You don’t have to wait for treatment, so in areas where heartworms are more prominent, you won’t have to worry.

If you have a Collie, you may want to consider an alternative to the main ingredient in Heartgard. Likewise, if you want a flea treatment as well, Sentinel might be a better choice. However, overall Heartgard offers you excellent value for the money.

For cats, there’s only one option Heartgard. Sentinel isn’t rated for cats and for the moment, there isn’t an option there.

Both options offer good value for the money, but Heartgard should cover your needs without hitting your wallet so hard.

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7 Treatment Application Tips

Helping your pet take the medicine may be difficult. Here are a few things to keep in mind when you’re administering the treatment and what to consider overall.

Treats And Dosages

Your dog may love its normal treats so try feeding a treat, feeding the dosage, and then feeding another treat. Your dog may be so excited that it takes it right away.

Put It In A Food

Sandwich the treat in a piece of palatable food. Fix another piece of the food. Give your dog the non-medicine portion first. Give the medicine portion next. Your dog should take it without much to do.

Make It A Game

If your dog loves games, you could try playing one for the treat. Take a piece of food and wrap it around the medicine. Playfully make your dog wait for the treat or do a trick. You could also hide it in one hand.

Set Reminders

If you have trouble remembering to give your pet the heartworm preventative, setting an alarm can help keep you on track. Reminders let you know that it’s time to give your pet the next dose so you don’t have a lapse in treatment.

Automate It

Many companies online can have an automated system that will send your treatment right to your door. When it arrives, that’s a great way to remember that it’s time for your pet to receive medication. It’s easy, and you don’t even have to remember to get the dose from your vet. It can also be a little easier on your wallet because many stores will have a slight discount for automatic shipping.

Natural Treatments

There are no natural treatments for heartworms. Some websites out there will give you holistic treatments, but once your dog is infested, you need to see your veterinarian. Prevention includes protecting your dog from the mosquito that carries the larva, and you’ll need heartworm prevention that really works.

Indoor Pets

Even pets who indoors still need a heartworm preventative. Pets can come in contact with mosquitos carrying the larva even if they’re outside only sometimes. It’s essential that your indoor pet is treated to prevent the deposited larva from growing to the adult stage. It interrupts the life cycle so that your pet is protected.

Do not rely on the fact that your pet is predominantly indoors to allow you to lapse in your treatment. Even a responsible pet owner with an indoor pet can find themselves with a heartworm positive pet.

Final Thoughts

Heartworm in cats medication is vital for your pet’s health and wellbeing. The effects of heartworms can be devastating for a pet, and the treatment for an infestation is far over what the cost of the preventative would be.

Indoor pets are just as susceptible to heartworms, so don’t get taken by surprise here. There are lots of options for heartworms including spot-on medications, so you wouldn’t have to decide just on chewables. However, we love Heartgard chewables for their ease and value for the money. Whatever you choose, it’s vital that your pet is covered.

Has your pet ever been heartworm positive? What steps have you taken to prevent this situation or what did you have to do to cure your pet? Let us know in the comments below.

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