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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 $42.99 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 (mil¿-beh-my¿-sin ox¿-eem) and Lufenuron (lew-fen¿-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 4.4 5 584 591
    Excellent product! Sentinel works very well to prevent heartworms and other worms as well. It also is a great flea prevenative. HIGHLY RECOMMENDED! 05/14/2010
    All Good The best phone service, support and follow-up. 05/13/2010
    great service great service, great price match, so easy-one 3 minute phone call and my Sentinel was on the way. have used this product for 10 years. No fleas or heartworms-one product does it all. 05/09/2010
    Great product This has worked on both my dogs since I got them. I love this product. I feed them the pill with a piece of cheese and haven't had a flea in my home in 15 years.......CAH 05/09/2010
    Great Purchase I've put both Ada and Cece on Sentinel - it works great and getting it from you is so easy. Thank you for the terrific service. Neither of the dogs have had fleas, ticks or heart worm - it works great. I just put it in some peanut butter and they love it. 05/08/2010
    Love it!!! Jenny was on the "other " topical treatments for fleas/heartworms. Now that it's summertime, Jenny loves being in the water, therefore, the treatments were not working. I couldn't keep her dry for days. Sentinel has solved our problem. It works great, no fleas and no worries. 05/08/2010
    Sentinel easy I have put all my dogs on sentinel due to it being so easy. I give the pill once a month and don't worry anymore. I have never had a problem with fleas or heartwork for 13+ years I have been using the product. The only thing is I have to give with cheese to the dogs they really don't like the taste none of the three I have used it on. 05/07/2010
    Love Sentinel We had problems with Heartgard--everytime Bentley took the meds they would come right back up about 4 hours later. The vet suggested sentinel--Bentley is very pleased with his new heartworm medication, 1 pill in some cream cheese and he's a happy (and protected) puppy!!! 05/02/2010
    thumbs up I have used Sentinel for ten years. I am a foster mom for a rescue group and use it on all my fosters. If a flea does hop onto my dog, I know that I will NOT have an outbreak in my home. Great relief! It's like birth control for fleas! 05/01/2010
    great Have used Sentinal for about 8 years. No fleas on dog. No signs of heartworm per blood tests. Easy to use. Pop a pill in his mouth and follow with a snack. No upset stomache noted. 04/30/2010
    I remember when... I am always thrilled with Sentinel. At least thirty five years ago, I had a lovely sheepdog named Rebel. My vet said his hair was too long to bother to check him for heartworms. By the time, I talked him into it anyway, Rebel had heartworms. We went through the treatment, Rebel was cured, but he was never the same. The treatment took too much out of him. He probably died five years or so early. I never miss a Sentinel for any dog I've had since it became available!! Thanks. 04/30/2010
    I have been using Sentinel for my various combination of dogs since 1992. We've never had a flea either in the house or on my pets during that time. My vet has stopped selling this product in his office, but I am so pleased with Sentinel that I buy my tablets from Pet Meds. My dogs love the taste (i.e. no problem getting them to take it), 04/27/2010
    Great product Our dog Sandy has been using Sentinel for 3 years. I never have to worry about heartworms or fleas. She has had no side effects at all. While I have purchased from other sites I will be returning to 1800PETMEDS. They were quick and the easiest website I have ever used! 04/27/2010
    great product for my girls Sassi is 14 and she is a westie and Sandee is12 and she my wonderful yellow lab.I have been giving them Sentinel for a long time.and it is a great product .My girls never had a flea on them,and it protects them from heart worm . ONE piece of cheese I give them with the pill keeps them happy and healthy.thank you pet meds for the best prices and quick delivery, sassi and sandee thank you too. 04/26/2010
    Great Product! I have a 9# shih tzu that is sensitive to many products. Have been giving her Sentinel for the last 8 years with no reaction or problems. I do have to hide it in a piece of cheese because she will not take it on it's own. You are suppose to give with food anyway. 1800petmed had the best prices and fast shipping. Will continue to purchase from them. 04/24/2010
    Great Product!! I have used Sentinel on my Maltese dogs for over 13 years. I won't use anything else. They tolerate it well, and have never had any side effects. With four dogs, we have never had a flea problem and don't expect to. We keep the dogs on it year eliminates the need for another proceedure and expense every year by them not needing to be tested for heartworm prior to restarting Sentinel. 04/24/2010
    Sentinel review Was given this by his vet. finished her 1st set and decided to get her next set from pet meds. Since the price is much cheaper than getting it from her Vet. 04/22/2010
    Great product! Hunter has been on this med ever since he was old enough to take it. I got him from someone who's dogs had had a litter of puppies that they didn't want. When I picked him up he was covered in fleas and had every type of intestinal parasite possible. Since he started Sentinel he has been flea and worm free (except for a tape worm, which Sentinel DOESN'T guard against). It's a great price for being several meds in one. Hunter loves the taste and thinks it's a treat! I'll always purchase this product over any other. If only it guarded against ticks, too....! 04/20/2010
    Zoey's Sentinel Zoey came to me via an animal rescue center. She is small - about 7 pounds - and has some problems with allergies. Her Sentinel does its job well without any allergic side effects. 04/19/2010
    Sentinel I would recommed sentinel to any dog owner it helps keep Gizmo healthy and it also helps with fleas it's a good product. 04/18/2010
    Wonderful Product Sam will be 2 yrs old in August. He's been on Sentinel since he was a baby and for the first time in my life (I'm 70) I have a dog that is flea and worm free. And that's important when you live in the deep south. 04/18/2010
    Best Ever I have a 9yr old Italian greyhound and have been using Sentinel for around 8 of those years. Have never seen a flea on her and always great checkups The taste she doesn't like but I wrap it in a peace of cheese and no problems.. I highly recommend this product to the fullest. 04/18/2010
    Sentinel Best product I have found to keep heart worm and Fleas away. 04/17/2010
    Sentinel Effectiveness We live in a rural area on 14 acres and have tried everything for fleas. We tried Sentinel and were overjoyed by the results. There are no more fleas and we appreciate the extra coverage for heartworm protection. Thank you Pet Meds 04/17/2010
    Wonderful heartworm preventative I got Pepper(now a 2 1/2 y/o Miniature Schnauzer) from a shelter, where she had been rescued from a puppy mill at appr. 6-7 mo. Her fear issues are still present, although we have been able to break through some of them. She seams fine, but is not terribly active. I am very happy with the Sentinal. It's easy to give and seems to taste good. Such easy protection for such a horrible disease. 04/15/2010
    Sentinel It may not be the cheapest medication out there, but it is well worth it! The fleas alone run high here in my area and I have two dogs to protect. I like Sentinel's wide range of protection and my dogs have been very healthy. Plus it saves money each yr not having to test for heart worms. 04/15/2010
    Sentinel Our 13-year-old Schnoodle Buddy has been on Sentinel for ten years and has done very well on it. He is active, social and healthy. He enjoys daily trips to the dog park and other dog owners say he appears younger than his actual years. I would and have recommended this product to friends and family. 04/14/2010
    Schatzi is a 12-1/2 year old Miniture Schnauzer and she has been on Sentinel since she was old enough to take the product. She has done remarkably well on the Sentinel and Missing Link Plus. At almost 13 years of age she is still very active - plays frisbee and takes 3 - 1 mile walks a day, loves children, other dogs and cats. Hopefully, she'll be around for years to come. She's spoiled rotten and we wouldn't have it any other way!!! 04/13/2010
    wonderful product Our Border Collie is 3 years old. He is healthy because of the products such as Sentinel and Omega 3 pills we buy from Pet Meds. Florida being a Tropical Climate is hard on pets, during the heat of summer. We never have a problem with fleas. Living in a gated community, Apache is always on a lease when he goes outside.. Pet Meds deliver on time and the prices are great. 04/07/2010
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    348 Questions · 641 Answers

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    1 week, 2 days ago
    Answer this question
    0 answers

    Overdose ???

    We are away for 3 months this winter. I brought 3 months supply of Sentinel with us for our mixed breed 37 lb 3 year old dog. She gets car sick so I also brought Bonine per our vets recommendations.. A few days ago before taking her in the car I accidentally gave her Sentinel instead of Bonide. She threw up in the car but I just thought the Bonide wasn't working. Then I realized my mistake. I only have one Sentinel pill left and I should have two for dosing on Feb 15 and March 15. What should I do? .
    1 week, 3 days ago
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    4 weeks, 2 days ago
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    Thank you for your question. There are six doses per pack.
    4 weeks, 2 days ago
    Maureen PetMeds Pro
    Pompano Beach, FL
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    1 month, 1 week ago
    Houston TX
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    there are times when both comfortis and sentinel are used together. The ultimate decision is up
    to your vet since both are prescription items.
    1 month ago
    Linda M 1800petmeds pharmacist
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    1 answer


    I have been using Sentinel for awhile now and have noticed my dogs are scratching. I put the flea comb to them and they have a few fleas. Not many but still they scratch. Can I use frontline or something else to rid us of the fleas ?
    1 month, 1 week ago
    Answer this question


    Be careful, this product only claims to break the flea cycle at the egg stage, it DOES NOT KILL ADULT fleas. The box even says so. So YES will still need another product to keep the adult fleas away or kill them. I still use Frontline, or Advantix for adult fleas. Advantix appears to be one of the few that claim to Repel fleas. The box also says Capstar may be used to kill adult fleas Temporarily, to speed up flea control. When I had another dog that brought fleas into the house I also had to use a Flea Spray around the whole house and carpet to kill the infestation in the house, rugs, corners and areas the dog slept. Be careful with those products and read the directions very carefully.
    User submitted photo
    3 weeks, 6 days ago
    Northern Indiana
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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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