Sentinel vs. Trifexis: Which All-in-One Preventive Is Best for Your Pet?

Which heartworm preventative is right for your dog?

If you’re like most pet owners, you want to provide your pet with the best protection from parasites with the least risk, hassle (for you and your pet), and cost. To help you decide which all-in-one preventive is best for you, we’ve put together a comparison of two major all-in-ones: Sentinel and Trifexis.

Similarities between Sentinel and Trifexis

Both Sentinel and Trifexis:

  • Contain the active ingredient Milbemycin Oxime, so they both treat and control roundworms, hookworms, and whipworms and protect against heartworms
  • Are chewable tablets that should be given once a month
  • Require a prescription from your veterinarian
  • Can be purchased online at 1-800-PetMeds

Differences between Sentinel and Trifexis

  • Cost
    One dose of Sentinel costs about $5 less than one dose of Trifexis.
  • Age at which each can be administered
    Sentinel can be given to puppies at beginning at 4 weeks; Trifexis can be given to puppies beginning at 8 weeks.
  • Minimum weight requirements
    Sentinel can be given to dogs as small as 2 pounds; Trifexis can be given to dogs as small as 5 pounds.
  • Flea control properties
    Sentinel contains Lufenuron, which prevents flea egg development and ends the flea life cycle, but doesn’t kill adult fleas; Trifexis contains Spinosad, which kills fleas (it has been proven to kill 100% of all biting fleas within four hours).
  • Cautions
    You should be cautious when giving any medication to your pet. And make sure you mention any other prescription medications or supplements you’ve given your pet to your veterinarian so he or she can check for drug interactions. Both have the potential for drug interactions. Trifexis carries the following caution: “Serious adverse reactions have been reported following concomitant extra-label use of ivermectin with spinosad alone, one of the components of Trifexis chewable tablets.”
  • Side effects
    With Sentinel, side effects are rare, but they can occur and may include vomiting; Trifexis may cause vomiting, and other side effects are less likely but possible.
  • Customer reviews
    Sentinel has a 4.4-star rating average from online shoppers and Trifexis has a 3.7-star rating average from customers.

We hope that this comparison has helped you decide which all-in-one preventive is right for you. Once you’ve decided, we hope you’ll visit 1-800-PetMeds for all of your pet supplies. Happy shopping!

Update 11/13/2013:  According to the FDA and Eli Lilly, Trifexis is safe and effective when used according to label instructions.  Unfortunately a small percentage of dogs may experience adverse reactions when taking this or any medication.  We encourage pet owners to consult their veterinarian before administering Trifexis or any other medication to their pets.

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  1. Our 10 year old, 17 lb , Lhasa Apso has been taking Trifexis since for most of his life. He always took it without
    hesitation when wrapped in cheese, BUT about 4 months ago he started refusing it, and now I can’t get him to take it,
    no matter how I try to disguise it. I am wondering if the drug maker changed the formula, because I don’t remember it smelling so bad until recently. Anyway, I force fed it to him last few months, but am going to ask vet for alternative, because
    the battle to get him to swallow it is too much.

  2. Same here Duane! I appreciate the benefits of Trifexis but I shouldn’t have to battle it every month. Why can just they make it taste better?

  3. Or just make it smaller w/o all the fake “beef” that all dogs can obviously smell through!! Life is short and to force feed a huge pill like that down my poor baby’s throat is horrible. If I break the pill in half it’s just as bad and now two traumatic episodes of pill shoving.

    If anyone has a substitute they recommend – plz lmk!!!

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  7. I agree something has changed with Trifexis. It has a very strong, unpleasant chemical smell. It is torturous to administer. My dogs hate it. I have to grind it and sprinkle on something VERY tasty like liver and even then they are reluctant to eat it. Plus Trifexis pills are available in 20lb (dog weight) increments, up to 60lbs. Over 60lbs and your dog gets a pill for a 120lb dog. You can’t break into pieces and administer because Trifexis does not guarantee that the medicine is uniformly distributed in the pill. I am switching to Sentinel. Hopefully, that will be easier to administer to my 2 large GSD dogs.

  8. Try using some ice cream that softens up a little bit, put the pill inside and then it goes right down their throat if you push it in the back!

    And as an added treat and incentive, I give the dog a little extra ice cream in the bowl so it kind of looks forward to it and certainly doesn’t mine The smooth ice cream going down his throat with the pill inside!

  9. As others say, Trifexis is obviously gross for dogs to eat. The first one was identified from my home made concoction of liver, tripe and other yummy ingredients, and spat out. These are so expensive. I just lost $20. The second I massaged down the throat. For the price they should be able to make this pill more palatable. Heck, shouldn’t be difficult. My dog will eat shit.

  10. Trifexis and Revolution are also two amazing products. Both Trifexis and Revolution are excellent product choices for any pet parents. Besides, the costs of both these products are very comparable.

  11. My dog never used to throw up, but now he does when he is given this medicine. I will definitely find a different brand. Like the one guy said, it can’t be that hard to make it a flavor a dog will eat…!

  12. Since the very beginning I battle my dog to take it, smells bad like dirt and chemicals anyways my dog hates it. I ground up the pill and mix it with peanut butter and have to trick my dog to take swallow to get a treat, so is a monthly battle I have to dealt with.

  13. If these dogs don’t want the trifexis maybe it’s nature saying it’s not safe for them.

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