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Monthly heartworm and flea prevention in the convenience of a tablet.
  • Prevents heartworm disease
  • Controls flea population
  • Controls hookworms
  • Removes and controls roundworms
  • Removes and controls whipworms
  • Beef flavor tablet
  • For dogs only


    Q & A
    Starts at $40.84 Ships in one business day or less
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      Product Info   How to use   Ingredients   Customer Reviews   Q & A  

    What is Sentinel?


    Sentinel is the only monthly oral preventive that guards against heartworms, adult roundworms, adult hookworms, whipworms, and prevents the development of flea eggs. Sentinel requires a prescription from your veterinarian.

    Comes in palatable flavored tabs
    Easy to administer just once a month

    How it works:
    Milbemycin oxime eliminates the tissue stage of heartworm larvae and the adult stage of hookworm, roundworm, and whipworm infestations. Lufenuron, the other active ingredient, is an insect development inhibitor that breaks the flea life cycle by inhibiting egg development. Lufenuron prevents most flea eggs from hatching or maturing into adults and thus prevents and controls flea populations by breaking the life cycle.

    Sentinel may be given along with Capstar, which treats flea infestation.

    Side effects are rare, though some animals may exhibit depression, drowsiness, vomiting, itching, hives, loss of appetite, diarrhea, or seizures. If these or other symptoms develop contact your veterinarian. Its important to maintain good personal hygiene, since humans can contract hookworms and roundworms. Its also important to eliminate fleas and to not feed your pet uncooked meat or fish. To prevent re-infection, clean up stools on a daily basis. Consult your veterinarian for pregnant or lactating dogs.

    More Information:
    Brand Name
    Sentinel (Novartis)
    Generic Name
    Milbemycin Oxime (milí-beh-myí-sin oxí-eem) and Lufenuron (lew-fení-your-on)

    What is the most important information I should know about Sentinel: Sentinel is a prescription medication FDA-approved for use in dogs. Sentinel is available as artificial beef flavored (derived from pork and soy protein) chewable tablets. This medication should be given once a month year-round.

    What is Sentinel: Sentinel is given once a month for the prevention of heartworm disease in dogs. Sentinel also protects against hookworms, roundworms, and whipworms. Sentinel is also used to control fleas by preventing the development of flea eggs. Sentinel does not kill adult fleas. The American Heartworm Society recommends that heartworm prevention be used year-round. Sentinel may also be used for purposes other than those listed in this guide.

    What should I discuss with my veterinarian before giving Sentinel to my pet: Tell your veterinarian if your pet has ever had an allergic reaction to the medication.

    How should this medication be given: Give Sentinel exactly as directed by the veterinarian. If you do not understand the directions ask your pharmacist or veterinarian to explain them to you. The usual dose of Sentinel for dogs 2 to 10 pounds is 2.3mg/46mg, 11 to 25 pounds is 5.75mg/115mg, 26 to 50 pounds is 11.5mg/230mg and 51 to 100 pounds is 23mg/460mg given once a month year-round. For dogs over 100 pounds give the appropriate combination of tablets. Heartworm testing should be performed prior to the start of prevention therapy. If your pet is off Sentinel for 6 months or less, re-start the medication and test after 6 months since microfilaria, that take 6 months to mature, will result in a positive test result. Store Sentinel at room temperature. Do not remove the tablet from its wrapper until ready to give the medicine. Keep this medication away from children and pets. Consult your veterinarian for pregnant or lactating dogs.  

    What happens if I miss giving a dose: Give the missed dose as soon as you remember. Do not give a double dose of the medication.

    What happens if I overdose the pet: Seek emergency veterinary medical treatment. Symptoms of overdose may include depression, drowsiness, vomiting, loss of appetite, diarrhea, hypersalivation, seizures, and weakness.

    What should I avoid while giving Sentinel to my pet: Because humans can contract hookworms and roundworms from animals, it is important to maintain good personal hygiene. It is also important to eliminate fleas on your pet and in the household and to not feed your pet rodents or uncooked meat or fish. To prevent reinfection, daily cleanup of stools is recommended.

    What are the possible side effects of Sentinel: Side effects of Sentinel are rare although some animals may exhibit depression, drowsiness, vomiting, itching, hives, loss of appetite, diarrhea, hypersalivation, seizures, and weakness. If these or other symptoms develop contact your veterinarian.

    What other drugs will affect Sentinel: While Sentinel is safe to use in dogs at risk for MDRI-allele mutation (Australian Shepherds, Collies, Shelties,etc.), unless tested normal, caution is advised if the pet is also being given amiodarone (Cordarone), azole antifungals such as ketoconazole, carvedilol (Coreg), cyclosporine (Atopica), diltiazem (Cardizem), erthromycin (Ery-Tabs) or clarithromycin (Biaxin), quinidine, spironolactone (Adlactone), tamoxifen, and verapamil (Calan). Do not give Sentinel to your pet if already giving an alternate heartworm medication.

    Where can I get more information: Your pharmacist has additional information about Sentinel written for health professionals that you may read.


    Give Sentinel Flavor Tabs once a month on the same day of each month year-round.
    Sentinel Flavor Tabs is for use in dogs only. Do not give to cats.
    Watch your dog closely following dosing to be sure the entire dose has been swallowed. If it is not completely swallowed, give one more full recommended dose as soon as possible.
    Tip: Do not remove Sentinel from its wrapper until ready to give to your pet.
    Pet Weight Dosage
    Dogs/puppies: (4 weeks of age or older)
    2-10 lbs Give 1 Flavor Tab every month
    (Brown Box)

    11-25 lbs Give 1 Flavor Tab every month
    (Green Box)

    26-50 lbs Give 1 Flavor Tab every month
    (Yellow Box)
      51-100 lbs Give 1 Flavor Tab every month
    (White Box)

    Over 100 lbs Give combination of Flavor Tabs based on weight
    Storage: Should be stored at room temperature between 59° and 77° F.
    Sentinel Brown for Dogs 2-10 lbs:
    Active Ingredient (per tablet) Amount
    Milbemycin Oxime 2.3 mg
    Lufenuron 46 mg

    Sentinel Green for Dogs 11-25 lbs:
    Active Ingredient (per tablet) Amount
    Milbemycin Oxime 5.75 mg
    Lufenuron 115 mg

    Sentinel Yellow for Dogs 26-50 lbs:
    Active Ingredient (per tablet) Amount
    Milbemycin Oxime 11.5 mg
    Lufenuron 230 mg

    Sentinel White for Dogs 51-100 lbs:
    Active Ingredient (per tablet) Amount
    Milbemycin Oxime 23 mg
    Lufenuron 460 mg

    Sentinel 4.5 5 554 561
    quick, easy, and dependable service. 04/03/2010
    Benefits of Products I wanted to let others know that the combination of sentinal and comfortis has helped so much with Murray's itching problems. He used to chew on himself etc til I started him on Comfortis, having been on Frontline before. And, Sentinal works well with Comfortis. I would recommend these to others who have pets with the allergy and itching problems. 03/29/2010
    Great product We have used Sentinel for years and it's very effective for everything it states it combats. The dogs eat and digest it well too. 03/23/2010
    Sentinel I love the fact that I can give Brandie 2 meds in one pill. It's so easy to just put it in her food, or give her a special breakfast of a scrambled egg. I also had another dog on this med, and was very pleased with it. I would recommend it to everyone. 03/22/2010
    Experience is proof We have been using Sentinel for 5 years on our beloved dog and have no complaints about the product. Our dog is active, playful and loves to run around in our backyard. Unfortunately some of our neighbors let their animals run loose plus nature critters (ie, racoons, squirrels, rabbits and skunks) also sometimes appear in our yard. We have had no problems with our dog acquiring unwanted fleas, ticks, etc. and we have absolute faith in Sentinel to keep him healthy. Thank you for your great product! 03/21/2010
    Great product I have 2 min schnauzers and 1 golden retriever on Sentinel. All take it like it is candy. Their checkups were negative, so it is doing it's job. 03/18/2010
    HOOK WORMS Have used the product for about a year - dog seems to like the taste - but then again she'll anything. Have had no problem with fleas and recent heartworm test was negative - however, she was diagnosed with hook worms - very disappointed - since that is the reason i chose this product over others. 03/17/2010
    Not effective for fleas I purchased this product because it stated that it was effective to combat both heartworm and fleas. Maybe it worked for haertworm, but it defenitely did not work for fleas. I had to take my dog to the vet 2 months ago because she had a flea infestation. We had to purchase another medicine only for fleas that she takes once a month. 03/11/2010
    Price Match The product has been great for Maxie. Suggest you Price Shop the internet for the best price and then get a price match. Maxie likes the cookie that comes with the order. 02/23/2010
    Great service Only place I would buy his preventative medicine! Rocky loves the biscuit that comes with the package! 02/22/2010
    I would buy this product no where else. I have two dogs. One 9 yr old shepherd mix and a 3 yr old adopted Maltese. I bought the appropriate weight of Sentinel flavor tabs for each dog from PetMeds for my vet was charging me almost twice the price for the same product. In the future I will continue to purchase this product from PetMeds. Simple to order on line, convenient and arrived to my home within a few days. 02/22/2010
    Love It I love this product,the best thing they ever come up for fleas and works on heartworms as well. Higly recommend this product. Don't waste your money on other flea products,because this one is # 1. 02/21/2010
    Sentinel I have 3 baby's and all are on Sentinal everyone is doing great on it no more fleas haven't had a problem with them are any worms since . Love it Thanks 02/20/2010
    Best Decision Ever I tried over-the-counter and prescription flea meds my local vet had available. Nothing kept the fleas away for an entire month. My Vet kept telling me you really need to use the liquid meds (Advantage) every three weeks not just every month. That became expensive. I finally looked up Sentinal which was a tablet to treat fleas and heartworms. I used Capstar with Sentinal the first month and Now for half the cost I was paying (heartworm/fleas)- I use only Sentinal. It works Great!! I only order through PetMeds because for some reason local vets do not carry it. 02/18/2010
    I live in East Texas, where fleas and mosquitoes can be a year around problem. Sentinal works great for my German Shepherd, who roams our 12 acres daily, exposed to the elements. ‚ÄúMax‚ÄĚ takes her Sentinal easily, with a dog treat followed, and it is a non-messy, once a month product that is very effective. I recommend Sentinal for any dog!!! 02/16/2010
    I have had all of my dogs on Sentinel for years, and have been very happy with the results. Occasionally during the summer months, or after they have been on vacation with us to flea-infested areas, I have had to use Capstar to kill some fleas they picked up. For the most part, they have been free of fleas, and my house has never been infested with them. 02/14/2010
    Best worm & flea preventive I have used sentinel for years. I have used it for my 8 yr old jack russell & my 3 yr old akita since they were pups (I also used it on my deceased 13 yr old akita) We never had a problem with worms or fleas. My Jack Russell eats it herself. My akita will lick off the coating and leave the pill so I have to place the pill on the back of his tongue. Problem solved. I would recommend this product to every pet owner. The cost is $$$ but less expense than using heartworm & flea preventiion meds bought separately. 02/14/2010
    Works for us We have had our 3 Yorkies Gizmo, Jasmine & Raizin on Sentinel their whole lives. It sure does the trick in keeping the fleas away and they never have any worm problems. I highly recommend this product. I used to buy directly from my vet but it is about $3.00 cheaper thru this site, plus no tax, free shipping and I can buy a year at a time. No extra trips back to the vet to purchase every 3 months. 02/10/2010
    Great Product I got my Crescent last Jan.14,2009 and I have had her on Sentinel since then. She has nver had a flea on her and it works great for heartworm...and etc. 02/10/2010
    Very Happy with Sentinel - It Works !! Willie is a Malshi (half Maltese/half Shih Tzu). Sentinel is the only product I use. He's been on Sentinel ever since he came to our family as a new born puppy, so I know no other product and reason I have never switched is because Sentinel works. I have looked around believe me to see if I could find something equivalent to Sentinel but less expensive . . . no such luck. Sentinel does it all, too. I don't even have him on a separate flea product either. That's not to say he may not have an adult flea from time to time bothering him and if I see he does, I will give him a Capster pill which compliments Sentinel quite well, but normally he is only on Sentinel. I would highly recommend this product -- you won't be sorry. Shih Tzu/maltese are sometimes prone to sensitivities, so I keep my eyes open at all times thinking he m ay have a negative reaction, but he's never had one to Sentinel, so just another reason I have kept him on it. IT DOES WORK FOLKS !!!!!! 01/31/2010
    Too good to be true I put off using Sentinel for a long time. I just use to use the Heartgard plus until I realized that all of the flea control products I was using was not really working. Even though all three of my dogs are inside dogs, I still was seeing more and more fleas. It wasn't long after starting the Sentinel that I noticed a reduction in fleas and eventually virtually none. I am so pleased. It is a little more of a challenge to get the dogs to take the Sentinel since it is in pill form and not a chew tab like the Heartgard but I just find something to wrap int in and they swallow it. 01/30/2010
    Tipper & Rugrat are doing fine on Sentinel Been on it for years no problem giving it to them they love it. 01/22/2010
    Dogs clear 2 large Australian Shephers been on Sentinel for years. Tests are completey clear. Great product. 01/22/2010
    Worth it While vets and animal hospital workers may refer to Sentinel as nothing more than 'flea birth control,' I say, one flea, the flea dies and life is good. Been using Sentinel for around 15 years with 8 large dogs (dalmatians and retrievers) and am very happily satisfied with the product. Most important - no heart worms! 01/22/2010
    Have not had any problems for 2 years Both my pups have been taking Sentinel for almost 2 years and I have not had any problems. Both dogs gobble it up with no problems and even do tricks when I have it in my hand. So far I have not had anything to complain about. 01/19/2010
    Don't bother This product is supposed to prevent flea infestations, worms and heartworm. So far we had a flea infestation and 3 days ago my dog was diagnosed with having whipworms. He has gotten this medication on the 1st of the month every month since we got him. Now I am very worried that he could have heartworm since it didn't protect him against the other parasites. I don't trust this product. This dog was already treated for heartworm before we got him and I fully understand the importance of him getting him medication regularly. 01/17/2010
    Recommend Joey could not take other brands due to health history from his family line. Sentinal has been very easy. One pill a month and I haven't had to worry at all. Joey and I love to walk and run. I am pleased to have an easy remedy to preventative health care. 01/15/2010
    Definitely Recommend I've tried a heartworm preventatives and sadly to say she still got infected. I'm sure it could of been transmitted by stepping on their own _____. However, the manufacturer did stand behind their product and paid for Elsa's vet $$$$ bills for treatment - she fully recovered. That scared me that, I switched to Sentinel. Elsa has been on Sentinel for 6 years now and faithfully clear from any heartworms or fleas, etc. She's always ready to take her tablet right out of the seal packet. Happy Lab and Happy Customer. P.S. This time I make sure I wash all my dogs paws before they come in the house and pick up right after they take care of their business constantly. 01/06/2010
    may be cancer causing? i have two dogs who have been on Sentinel their entire life. Ages 12 and 11. I never had flea trouble, so i know it works. However, both dogs have osteosarcoma. i will always wonder if it was the flea meds. 01/05/2010
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    339 Questions · 627 Answers

    Ask & Answer.

    Talk to other pet lovers about this product.

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    2 weeks, 6 days ago
    Answer this question


    Please contact your veterinarian.
    5 days ago
    Stephanie Duesler, Pharm. D, MBA
    Vote as Best Answer
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    Since my puppy is protected from fleas and heartworm, what is a good prevention medicine that can be used in conjunction with Sentinel?
    2 weeks, 6 days ago
    Answer this question


    Bravecto will protect your pet against ticks and can be used with Sentinel
    5 days ago
    Stephanie Duesler, Pharm. D, MBA
    Vote as Best Answer
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    3 weeks, 1 day ago
    Answer this question


    Thank you for your question. No, this does not control mosquitoes.
    2 weeks, 6 days ago
    Maureen PetMeds Pro
    Pompano Beach, FL
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    Hello, hope you are doing well. Friends told me to reach out to you since you do such a great job in customer service. I have 2 labs to care for. What is the effectiveness of Sentinel (Lufenuron/Milbemycin oxime) versus Trifexis (Spinosad/Milbemycin Oxime). The ingredients are different but I don't have enough information on the second ingredient in Sentinel. Any help please. Thank you.
    1 month ago
    Answer this question


    I don't know about Trifexis but save your money do not buy Sentinal! It does not work. I learned this the hard way.
    3 weeks, 2 days ago
    dog mom of 3
    Vote as Best Answer
    Thanks for Voting

    Both medications are effective to prevent Heartworms, roundworms, hookworms and whipworms. Their difference is the Spinosad ingredient in Trifexis kills adult fleas while the Lufenuron in Sentinel will only sterilize flea eggs instead of killing any adult fleas.
    4 weeks, 2 days ago
    Lilli Pharmacist
    Pompano Beach, FL
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    This information sheet is for educational purposes only and is intended to be a supplement to, and not a substitute for, the expertise and professional judgment of your veterinarian. The information is NOT to be used for diagnosis or treatment of your pet. You should always consult your own veterinarian for specific advice concerning the treatment of your pet. The information is not intended to cover all possible uses, directions, precautions, warnings, allergic reactions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for your pet. It is not a substitute for a veterinary exam, and it does not replace the need for services provided by your veterinarian.
    Note: Any trademarks are the property of their respective companies.
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