Sentinel vs Sentinel Spectrum For Dogs: Which one is Better?

Need to protect your dog from heartworms, fleas and intestinal parasites? You may not be sure what type of medication is right for your pup. There are a lot of different options out there, so you may be wondering which one will provide your dog with long-lasting protection, and ensure its happy, healthy life. In this 2024 comparison guide to take a look at which one is better: Sentinel vs Sentinel Spectrum.

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Heartworm can be lethal to dogs, and develop without any symptoms. Intestinal parasites may result in diarrhea and poor nutrition, and fleas can spread between your dog, other animals, and humans and transmit a variety of diseases. It’s important to make sure you and your dogs are protected from all of these issues – so that your family stays safe.

So, in this article, we’ll be taking a look at two different medicines which are often prescribed to dogs to deal with intestinal parasites, heartworm, and fleas – Sentinel, and Sentinel Spectrum. We’ll discuss everything you need to know, from the safety of each drug to its key effects, price, ease-of-use, and more.

Once you’ve finished reading this article, you’ll know everything there is to know about these two drugs – and you can consult with your veterinarian to make sure that you’re choosing the right medication for your pooch. Let’s get started now!

Key Differences Between Sentinel and Sentinel Spectrum

Sentinel and Sentinel Spectrum are both made by the same company, so they are actually extremely similar. However, there are a few differences that you should be aware of when shopping for one of these medicines. Let’s take a look at these now.

  • Active ingredients – Sentinel uses milbemycin oxime and lufenuron. Milbemycin oxime is a powerful drug that destroys the larvae and young stages of heartworms, and kills adult roundworms, hookworms and whipworms. Lufenuron is an agent that interferes with the reproductive ability of fleas, killing their eggs and larvae and preventing them from reproducing, thereby eliminating flea infestations.
    Sentinel Spectrum uses the same ingredients, but also adds praziquantel. Praziquantel is a drug that is extremely effective at killing tapeworms, and can kill both larvae and eggs as well as adult tapeworms in your pet. This means that, overall, Sentinel Spectrum provides more protection from intestinal parasites.
  • Safe age of initial application – Sentinel has been tested on dogs as young as 4 weeks and of 2 lbs in weight, and is safe to administer to your dog from this young age. Sentinel Spectrum, though, has only been tested in dogs as young as 6 weeks and 2 lbs in weight, so Sentinel may be a better option than you if you want to treat your dog from a very young age. Overall, though, this doesn’t really matter as much if you are not treating a puppy with one of these medicines.
  • Types of parasites treated – Sentinel treats a total of 5 common parasites – heartworm, roundworm, whipworm, hookworm and fleas. This means it provides quite a bit of protection for your dog, especially compared to some other medications on the market like Heartgard Plus. However, Sentinel Spectrum improves upon this even more, by also treating tapeworm. It is important to note, though, that neither of these medications will have any effect on ticks
  • Generic availability – It’s quite easy to find generic versions of Sentinel, which use the same active ingredients but are often quite a bit cheaper. However, this is not the case with Sentinel Spectrum, so this is something you may want to consider when shopping.
  • Price – Sentinel, being an older medication and a simpler formulation that uses only two active ingredients, is typically cheaper thane Sentinel Spectrum, but we’ll discuss this more in-depth in the section “What’s Cheaper, Sentinel Or Sentinel Spectrum?” later in this article.

As you can see, these medications do have some big differences, despite only being distinguished by the addition of a single additional active ingredient. Now that we’ve discussed the different properties of each of these drugs and how they compare, let’s take a deeper look at the qualities of Sentinel and Sentinel Plus.

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Key Features Of Sentinel

Sentinel vs Sentinel Spectrum

Sentinel has been recommended by vets by decades and is a highly-effective antiparasitic drug for dogs. Here’s what you need to know about it.

  • Monthly, chewable tablet – Sentinel is provided in the form of a chewable, beef-flavored tablet that incorporates both pork and soy protein, and is to be administered once per month alongside a meal. It’s delicious and readily accepted by most dogs, so you should have no problems treating your dog with this medication.
  • Simple to administer – To administer Sentinel, you just have to give your dog the chewable pill. Note, however, that your dog is supposed to chew it into pieces before swallowing. If your dog tends to swallow treats and food whole, you may want to crush it before feeding it to your dog.
    Regardless, many pet owners find that monthly oral medications are easier to administer than other types of anti-flea medications which are applied topically, as you don’t have to hold your dog still, or worry about the medicine being washed away prematurely.
  • Protection from 5 common parasites – Sentinel kills heartworm larvae (but not adult heartworms) as well as fully-grown roundworms, hookworms and whipworms. In addition, it disrupts the flea life cycle, killing larvae and eggs. Again, it will not kill adult fleas – but it is safe to use with most anti-flea medication that focuses on killing adult fleas.
  • Usable on dogs as young as 4 weeks, 2+ lbs – Sentinel has been tested extensively and can be used on appropriately-sized dogs as young as 4 weeks of age, so it’s a good option if you wish to treat your dog and keep it safe from fleas, intestinal parasites, and heartworm.
  • Dog-specific formula – Unlike some other medicines, Sentinel is specifically formulated for the needs of dogs, so it cannot and should not be used for other animals such as cats and horses.

Now that you understand more about the details of Sentinel, let’s move on and discuss Sentinel Spectrum in more detail.

Key Features Of Sentinel Spectrum

Sentinel Spectrum shares many qualities with Sentinel, but does have some unique attributes and features that you may want to take into account when shopping for the appropriate anti-parasite medication for your pup. Here’s a quick overview.

  • Monthly, chewable tablet – Sentinel Spectrum comes in a number of different sizes with different formulas, intended for dogs of differing weights. All Sentinel Spectrum doses are delivered in a chewable oral medication that’s beef-flavored and can be eaten just like a dog treat.
  • Easy to give to your dog – Most dogs love the flavor of Sentinel Spectrum, and it can be fed to your dog once per month. Feeding it to your dog with a meal is the best way to avoid potential side effects like nausea and vomiting, so take this into account when providing your dog with its monthly medicine.
  • Destroys tapeworm – Unlike Sentinel, Sentinel Spectrum contains praziquantel, which is an extremely powerful anti-tapeworm drug that can eliminate most tapeworm infestations quite quickly, and also eliminates the reproductive process of these parasites.
  • All-in-one protection – Beyond tapeworm, Sentinel Spectrum also destroys all of the same parasites as Sentinel, including juvenile heartworm and heartworm larvae, flea eggs and larvae, and adult hookworm, roundworm and whipworm. Ticks are the only common parasites that are not eliminated by this product.
  • Usable on dogs as young as 6 weeks, 2+ lbs – Unlike Sentinel, Sentinel Spectrum should only be used on dogs 6 weeks of age or older. Its safety has not been tested on dogs which are younger than this, or below 2 lbs in weight. Make sure you always consult with your vet to make sure that it’s safe to start using Sentinel Spectrum with your pup.

Though there are some similarities between Sentinel and Sentinel Spectrum, they are quite distinct – as shown by the information above.

What is Better for Dogs, Sentinel or Sentinel Spectrum?

If we had to pick one, we would have to say that Sentinel is safer and better for your dog, as it can be used from an age of 4 weeks, while Sentinel Plus can only be used on dogs 6 weeks of age and older. However, both are very safe and have minimal, rare side effects which can include:

  • Vomiting and nausea
  • Diarrhea
  • Drowsiness/depression
  • Hypersalivation (excessive drooling)
  • Muscle weakness
  • Itching/hives
  • Seizures

To make sure your dog does not suffer from these side effects, you should consult with your vet before using Sentinel or Sentinel Spectrum. In addition, always make sure you follow proper dosing instructions, and administer the medication regularly each month. Never give your dog two doses of medication, and make sure that you administer it alongside a meal to prevent your dog from becoming nauseated.

Both Sentinel and Sentinel Spectrum are safe to use on dogs which may have the MDRI-allele mutation – common in some types of Collies and Shepherds. However, there are some medications which may interfere with Sentinel and Sentinel Spectrum, like Coreg, Biaxin, Ery-Tabs, and Calan. Make sure you consult with your vet to make sure it’s the right choice, based on your dog’s other medications.

Finally, the safety of Sentinel and Sentinel Spectrum has not been tested on breeding, lactating and pregnant dogs. If you have a breeding dog, a stud dog, or a pregnant dog, you will want to consult with your veterinarian to make sure one of these medications is safe for your pup.

What’s Cheaper, Sentinel Or Sentinel Spectrum?

Sentinel is an older medication and has fewer active ingredients, so it’s cheaper to formulate, and the less expensive option overall. There are also a few generic medications that use milbemycin oxime and lufenuron, which are quite inexpensive, and can be purchased online from websites like

In contrast, Sentinel Spectrum is usually a bit more expensive, though the price difference is not very dramatic. Counter-intuitively, though, we think that Sentinel Spectrum is a better value – even though it isn’t cheaper.

Why? Because Sentinel does not protect your dog from tapeworm – so if you are concerned about tapeworm prevention, you’ll need to purchase an additional, anti-tapeworm drug, which will end up costing you more money than simply purchasing Sentinel Spectrum in the first place.

So, while Sentinel is technically cheaper, we think that Sentinel Spectrum offers a better overall value, as it helps you keep things simple, and provides protection from a wider variety of parasites.

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What’s Easier To Find, Sentinel Or Sentinel Spectrum?

This category is a tie. Both Sentinel and Sentinel Spectrum are extremely easy to find. They can be found at the vet, in pet pharmacies, online at websites like, and even at some large chain stores like Walmart.

Regardless of which medication is prescribed for your dog, you will have an easy time finding it for a great price, especially if you shop online at However, both of these medications require a prescription, so you’ll need to visit the vet before you start shopping.

Which One Is Better For Heartworms, Sentinel Or Sentinel Spectrum?

Both Sentinel and Sentinel Spectrum use the same active ingredient to treat heartworms and are equally effective. It is important to note, though, that neither medication will kill adult heartworms – you will need specialized treatment from a vet to eliminate adult heartworm infestations.

Instead, the ingredients in Sentinel and Sentinel Spectrum interfere with the ability of juvenile heartworms to grow into adult heartworms, killing them before they can fully develop and harm your dog. For maximum effectiveness, both must be administered every month for at least 6 months.

Which One Is Better For Intestinal Parasites, Sentinel Or Sentinel Spectrum?

Sentinel Spectrum is better for treating intestinal parasites because it includes praziquantel, which destroys adult tapeworms as well as tapeworm eggs and larvae. Sentinel does not have this ingredient and has no effect on tapeworm.

If you are looking for comprehensive protection for your dog, and want to destroy and prevent the growth of all major intestinal parasites including tapeworms, Sentinel Spectrum is definitely a better choice.

Which One Is Better For Fleas, Sentinel Or Sentinel Spectrum?

Both products use the same active ingredient, lufenuron, to treat fleas, so they are equally effective in this regard. Lufenuron is stored in the dog’s body fat, then transferred into adult fleas when they feed. In turn, it is transmitted to growing eggs through their blood, and larvae which feed on excrement – killing the eggs and larvae before they mature.

Again, it is important to note that Sentinel and Sentinel Spectrum do not kill adult fleas. However, these medicines are safe to use alongside common anti-flea medicines like Capstar Flea Treatment Tablets, which kill adult fleas.

Which Is Easier To Give My Dog, Sentinel Or Sentinel Spectrum?

This category is also a tie. Both types of medicine use a once-monthly, artificially beef-flavored chew that incorporates soy and pork protein – and are readily accepted by most dogs.

For proper administration, the medicine must be chewed thoroughly by your dog. If you are having difficulty getting your dog to chew Sentinel or Sentinel Spectrum, or your dog refuses to eat it, we recommend crushing the medicine into pieces and mixing it with a food or treat your dog likes – such as peanut butter, or meat gravy.

Whichever way you choose to administer the drug, you must make sure that your dog consumes and chews the whole dose. For this reason, we do not recommend simply adding the tablet to your dog’s kibble, as it may not chew or eat the whole thing. Administer the medicine under supervision, to make sure your dog chews and eats it properly.

Overall Winner Between Sentinel And Sentinel Spectrum

Our overall winner is Sentinel Spectrum. While it is a bit more expensive, it offers superior protection due to its ability to kill tapeworm. While Sentinel kills heartworm, fleas, roundworm, hookworm and whipworm, it does not have any effect on tapeworm. For this reason, Sentinel Spectrum is a much better choice for your dog, and it will provide more protection from intestinal parasites.

The only exception to this is if you have a dog which is 4 weeks old, and you do not want to wait until 6 weeks to begin administering its anti-parasite treatment. Sentinel has the advantage of being usable in younger dogs.

But in general, Sentinel Spectrum is a better choice. However, we always recommend that you consult with your veterinarian before choosing any kind of prescription medication for your dog. Depending on your dog’s unique needs, Sentinel Spectrum may be the right choice – or there could be another drug that is more suitable for them. Listen to what your vet has to say, and you’re sure to make the right choice.

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The Most Common FAQs About Sentinel vs Sentinel Spectrum

If you have questions about Sentinel and Sentinel Spectrum, or parasites and anti-parasite medication in general, we’re here to help. Here are some common FAQs on this subject. Read on, and educate yourself!

  • What if my dog weighs over 100lbs? Both Sentinel and Sentinel Spectrum come in tablets for differently-sized dogs, but the largest tablet is intended for dogs 51-100 lbs in weight. If your dog exceeds this weight limit, you must simply administer multiple tablets. For example, a 200 lb Great Dane may require two 51-100 lb tablets. Your veterinarian will ensure that you get the proper dosage when they prescribe Sentinel or Sentinel Spectrum for your dog, so as long as you follow their instructions, you’ll be all set.
  • What if my dog has side effects from Sentinel or Sentinel Spectrum? Side effects are usually rare and limited to nausea and diarrhea – and these can usually be avoided by making sure your dog eats Sentinel or Sentinel Spectrum with food.
    However, if you notice more serious side effects like lethargy, seizures, muscle weakness, or hives/itching/skin irritation, you should take your dog to the vet right away. It may be allergic to the medication and having a reaction to it, and you should get professional help to determine the source of the issue ASAP.
  • Can I stop using Sentinel or Sentinel Spectrum in the winter? Absolutely not. Even though your dog is less likely to be bitten by mosquitoes or to pick up fleas in the winter,  there is always a risk of parasitic infestation. In addition, both Sentinel and Sentinel Spectrum should be used for 6 months to provide complete protection against heartworms, because this is how long the juvenile worms take to develop into adult heartworms. Once your pet starts a medication like Sentinel or Sentinel Spectrum, you need to keep giving it the proper dosage each month, no exceptions.
  • What if I miss a month of treatment? It’s not the end of the world. If it’s been less than a month, just give your dog its next dose of Sentinel or Sentinel Spectrum as soon as you can, and begin administering monthly doses again, starting from this date.
    If you have missed two months or more, consult your vet to find out what you should do. Never give your dog two doses of Sentinel or Sentinel Spectrum. This could cause serious side effects like nausea and seizures.
  • Will Sentinel or Sentinel Spectrum kill ticks? No. While both of these medicines use an anti-flea medication, this will not work on other arthropods like ticks. Make sure to check your dog for ticks regularly, and consider using a different anti-tick medicine for more protection if you take your dog on hikes, into wooded areas, and in other places where ticks are common. Doing so is the best way to prevent issues like Lyme Disease, Rocky Mountain Spotted Fever, and other such issues associated with ticks.
  • Can I get worms from my pet? Yes. Some types of worms, like roundworm and hookworm, can be transmitted from your pets to you and your family. The best way to prevent this is with proper hygiene. Always wash your hands after touching pet waste, even through a baggie or gloves, or touching your dog anywhere near their its rear. You should also remove pet waste from your yard as quickly as you can, as some types of worms may be able to live underneath the soil.
  • Can my dog spread heartworms, or get heartworms from another animal? No. While parasites like fleas, roundworms, hookworms and whipworms can be transmitted to dogs from other dogs and animals, heartworms cannot.
    Heartworms are only transmitted by mosquitoes that bite infected dogs. The larvae in the dog’s bloodstream enter the mosquito, which spreads them into a new host once it bites another dog. This is the only way that heartworms can be spread, so you do not have to worry about other animals transmitting them to your dog. As long as you use medicine like Sentinel or Sentinel Spectrum monthly, your pup will be protected.
  • Should I use Sentinel or Sentinel Spectrum instead of my dog’s current medicine? If your dog is taking another medicine like Heartgard Plus, which does not protect from as many parasites as Sentinel or Sentinel Spectrum, you may want to switch. To make sure that it is safe for your dog to start using another medicine, we recommend consulting with your vet, and asking them if making the switch is a good idea for you and your pup.

We hope that the answers to these common questions have helped you learn more about common dog parasites. We know that this subject can be quite complex and hard to understand, so if you have further questions, we recommend consulting with your vet. They can explain everything that you need to know about protecting your pup from common parasites like heartworms, intestinal parasites, fleas and more.


Regardless of which medication appeals to you, or which one you may prefer for your dog, protecting your pup from parasites is extremely important. Heartworms are deadly, and fleas and intestinal parasites can interfere with your dog’s quality of life, and lead to serious diseases and health problems.

So, regardless of which medication you think may be right for your dog, we recommend scheduling an appointment with your vet right away – especially if your dog is not yet using any kind of anti-parasite medication.

Once you’ve consulted with your vet, you can decide which one of these medicines is right for you, based on their recommendations, and your dog’s own unique needs. So don’t wait. Get started today!

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