Worried about your dog and heartworm infection? Concerned about dog roundworm risk to children? Sentinel for dogs is a chewable tablet that solves these problems as easily as giving a dog a treat.

This anti-parasite product from Virbac is given once a month, with food, to protect your pet from internal and external parasites. Read on to learn more about how Sentinel can help your pooch!

What is Sentinel for Dogs?

Sentinel for dogs is an antiparasite product and dewormer. It’s designed to control flea eggs and larvae, preventing a flea population explosion. Importantly Sentinel also kills heartworm larvae, making it an option for heartworm prevention. In addition, this product gets rid of some common intestinal worms such as roundworms, whipworms, and hookworms.

Sentinel for dogs and puppies is a prescription product. It comes as a tasty tablet which most dogs accept as a treat. Designed to be given once a month, it should be administered with food.

If your dog’s heartworm protection has lapsed, always speak to a veterinarian before restarting a preventative. Not to do so could place your pet’s health at risk.

A Drug that will Kill those Parasites!

If your dog hates spot-ons or sprays, then the convenience of chewable tablet is just the thing. Sentinel is effective against a number of common parasites.

  • Flea eggs and larvae (Note: It doesn’t kill adult fleas, ctenocephalides felis)
  • Heartworms
  • Roundworms
  • Whipworms
  • Hookworms

In addition, Sentinel Spectrum contains praziquantel, which kills tapeworms. This is a good choice for the dog that scavenges or has lots of fleas (adult fleas often have tapeworm eggs inside them.)

How Does Sentinel Dog Medication Work?

Sentinel for dogs contains two active ingredients milbemycin oxime and lufenuron. These work in different ways to control parasites.

Milbemycin Oxime

This oxime is responsible for the worm control part of Sentinel.

Milbemycin works by scrambling the worm’s nerve transmission. This paralyzes the worms and kills them. It works against the larval, tissue stages of heartworm, along with the intestinal worms Toxocara (roundworms) Trichuris (Whipworm), and Ancylostoma (hookworm).


Lufenuron flea control work by stopping adult fleas from breeding. Lufenuron is what’s known as an ‘insect growth inhibitor’ and stops flea eggs and larvae from maturing. It’s important to recognize the difference between this and killing adult fleas.

With Sentinel, any adult fleas present are not killed but die of old age. But the good news is the infestation dies with that flea because the next generation of eggs don’t hatch out.

5 Facts You Need to Know!

  1. Give Sentinel with or after food:  An active ingredient, lufenuron, is absorbed better into the bloodstream in the presence of food. Giving Sentinel on an empty stomach is less effective.
  2. Sentinel stops fleas breeding:  Sentinel helps flea control by stopping this parasite breeding. It interrupts the flea life cycle by killing flea eggs and larvae. However, it does NOT kill adult fleas.
  3. You may need to add in a flea adulticide:  If you have a heavy flea infestation it may be necessary to add in a second product to kill adult fleas. For example, a dose of Capstar, another medicated tablet, will kill fleas within minutes. Team Capstar with Sentinel and you can control both adult fleas and the eggs hiding in the carpet.
  4. Sentinel Spectrum kills tapeworms: Sentinel Spectrum has an added ingredient, praziquantel. This makes it effective at killing tapeworms.
  5. Not effective against Ticks: Know that Sentinel’s spectrum of activity does NOT include ticks. If you are concerned about the risk of Lyme disease or other tick-borne infections, speak to your veterinarian about the most effective product for your needs.

Does My Dog Need Sentinel HeartWorm Meds?

Heartworm disease is a serious, life-threatening parasitic infection spread by biting mosquitoes. Protection against heartworm is essential for your dog’s long-term good health and your peace of mind.

There are many options for heartworm preventatives, of which Sentinel is one. The great thing about Sentinel is it’s easy to administer. And as a chewable tablet, there’s no sticky residue that could rub off on the furnishings and there’s no risk of it washing off if the dog goes for a swim.

Please be aware that giving a preventative product to a dog with active heartworm disease can endanger the dog. If there’s been a lapse in your dog’s protection, speak to your vet about how best to proceed.

It may be necessary to test the dog to check for active infection, before going ahead with any preventative product (not just Sentinel)

Side Effects!

All medications have the potential for side effects. Sometimes these side effects occur in dogs or puppies that are sensitive to one of the ingredients, or sometimes side effects only happen at high doses.

Sentinel for dogs is considered a very safe medication, but just like any med, it can cause problems in unlucky individuals.

The good news is that it takes an extreme overdose to deliberately bring about side effects. A safety study where adult dogs were given 20 times the recommended dose, didn’t cause any problems. The same high dose in young puppies produced shivers, whining, and wobbliness, but happily, these signs wore off after a few hours.

Occasional side effects that may happen if a dog is sensitive to one of the ingredients include:

If your dog shows these signs after taking Sentinel, contact your vet for advice.

Who Should Not Use Sentinel Flavor Tabs?

First, it’s important to know Sentinel products are extremely safe. It has been widely tested in both pregnant and nursing female dogs, and has a high safety margin for the unborn or nursing puppies. However, it is not strictly licensed to be given to pregnant or nursing dogs. This means to do so is at your own risk.

Sentinel for dogs is administered by body weight. The lower limit on the size of the dog is 2 lbs, so if the dog is lighter than this do not give Sentinel flavor or Sentinel Spectrum.

Puppies younger than 4 weeks, should also not be given Sentinel. The puppies small size and immature organs mean this medication is best not given until they are slightly older.

Nexgard Chewables Amazon or Sentinel Dog Tablets! Which Should You Buy?

Actually, Nexgard and Sentinel are a different as salt and pepper. The only similarity is they are both a chewable tablet. However, their spectrum of activity is completely different.

The main differences are that Nexgard kills fleas and ticks, including adult fleas. Nexgard does NOT protect against heartworm or other intestinal worms. If you have a flea and tick problem AND want to protect against heartworm, then Nexgard Spectra is the tablet to meet your needs.

When deciding between Nexgard and Sentinel, it’s best to first decide on your priorities. For example, if you have children and want to avoid roundworms plus protect the dog from heartworm, then Sentinel is the best choice. But if your main concern is preventing Lyme disease then chose either Nexgard (or Nexgard Spectra with the heartworm part.)

Trifexis for Dogs vs Sentinel for Dogs!

Trifexis and Sentinel are both designed to protect your dog against parasites such as the heartworm, hookworm, whipworm, and roundworm. However, it is important to remember that these products do have their differences.

To begin with, Sentinel Spectrum does not kill fleas. However, it does prevent the development of flea eggs and larvae should your pet have any.

Additionally,  Sentinel chewables work immediately whereas it may take up to 30 minutes for Trifexis to kill fleas.

The major difference between the two brands is not just the speed at which they begin to work, but the parasites they work on. Trifexis is able to kill fleas, larvae, and eggs, while Sentinel cannot.

Top 5 Antiparasitic and Heartworm Pills for Dogs

Each product has a slightly different spectrum of activity. Here are our top picks for chewable tablets for heartworm prevention. But the choice will vary depending on the risks your dog faces. If in doubt, chat to your vet who can advise which product best meets the dog’s needs.

  1. Nexgard Spectra:  Wins out because of the tick control
  2. Sentinel Spectra: Great for intestinal parasites in addition to heartworm.
  3. Milbemycin: A great broad spectrum dewormer, including for heartworm
  4. Valuheart: Like Heartgard but less expensive
  5. Heartgard: The first choice of many vets

Remember, if fleas and ticks are a problem then there are many flea pills for dogs available too!

Sentinel for Dogs: Reviews!

What do real-life owners who use Sentinel say about the product?

Well, Sentinel is one of those products that people love or hate (but mostly love!)

There are many devoted users who converted to Sentinel from spot-on products. They love the no fuss, no mess way that it’s given. They also love how it doesn’t irritate the dogs’ skin in the same way that some spot-on products do.

Sentinel for dogs also rates highly with owners of long-haired dogs. Again, it comes down to the convenience of an oral product, which is so much easier than hunting for the skin on a wriggly thick-coated dog.

The odd dissatisfied voice feels cheated that Sentinel doesn’t kill adult fleas. However, the product doesn’t claim to do this. Whereas, the savvy user describes Sentinel as a ‘slow burner’ at getting rid of flea infestations but never has a problem when used regularly.

What About a Sentinel Rebate

Did you know you can get rebates on sentinel products? As of 2018, Sentinel will offer a $10 rebate for 6 doses on their Sentinel spectrum chewable tablets and a $25 rebate on 12 doses.

If you’re interested in the Sentinel flavor tabs then worry not! For 6 doses you can receive a $7 rebate and for 12 doses you’ll receive a $20 rebate.

Remember, to qualify for a Sentinel rebate you will have to submit a form completed with both your invoice and coupon code. You can find these forms directly on the Sentinel pet website.