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Sentinel Flavor Tabs for Dogs

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  • Description
  • Ingredients
  • Directions
  • FAQ
  • Reviews


Sentinel Flavor Tabs is a preventive for heartworms, adult roundworms, adult hookworms and whipworms for your dog. Sentinel also prevents the development of flea eggs on your pet by breaking the flea life cycle. Sentinel can be taken along with Capstar for a more thorough flea treatment program. Sentinel requires a prescription from a veterinarian in order to be dispensed to your pet.

Key Benefits

  • Prevents heartworm disease
  • Comes in palatable beef flavored tabs
  • Easy to administer just once a month
  • Controls flea population
  • Controls hookworms
  • Removes and controls roundworms
  • Removes and controls whipworms


Sentinel Flavor Tabs are indicated for use in dogs and puppies, four weeks of age and older, and two pounds body weight or greater. Sentinel Flavor Tabs are also indicated for the prevention of heartworm disease caused by Dirofilaria immitis for the prevention and control of flea populations, the control of adult Ancylostoma caninum (hookworm), and the removal and control of adult Toxocara canis and Toxascaris leonina (roundworm) and Trichuris vulpis (whipworm) infections.

Lufenuron controls flea populations by preventing the development of flea eggs and does not kill adult fleas. Concurrent use of an adulticide product may be necessary for adequate control of adult fleas.

Without concurrent use of an adulticide, adequate flea control may not be achieved in dogs that have repeated exposure to flea-infested animals or environments.

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.


Active Ingredient (per tablet) Milbemycin Oxime Lufenuron
Sentinel Brown 2.3 mg 46 mg
Sentinel Green 5.75 mg 115 mg
Sentinel Yellow 11.5 mg 230 mg
Sentinel White 23 mg 460 mg


View Sentinel Flavor Tabs Drug Facts Sheet.

Sentinel Flavor Tabs are given orally, once a month, at the recommended minimum dosage of 0.23 mg/lb (0.5 mg/kg) milbemycin oxime and 4.55 mg/lb (10 mg/kg) lufenuron.

Dogs over 100 lbs are provided the appropriate combination of tablets.


To ensure adequate absorption, always administer Sentinel Flavor Tabs to dogs immediately after or in conjuction with a normal meal.

Sentinel Flavor Tabs are palatable and most dogs will consume the tablet when offered by the owner. As an alternative to direct dosing, the tablets can be hidden in food. Be certain the dog consumes the entire tablet or tablets. Administer Sentinel Flavor Tabs to dogs immediately after or in conjunction with a normal meal. Food is essential for adequate absorption of lufenuron. Watch the dog closely following administration to be sure the entire dose has been consumed. If it is not entirely consumed, redose with the full recommended dose as soon as possible.

Recommended Dosage Schedule
Body Weight Milbemycin Oxime Per Tablet Lufenuron Per Tablet Monthly Dosage
2 to 10 lbs 2.3 mg 46 mg 1 (Brown)
11 to 25 lbs 5.75 mg 115 mg 1 (Green)
26 to 50 lbs 11.5 mg 230 mg 1 (Yellow)
51 to 100 lbs 23 mg 460 mg 1 (White)
Over 100 lbs Give combination of Flavor Tabs based on weight

Sentinel Flavor Tabs must be administered monthly, preferably on the same date each month. Treatment with Sentinel Flavor Tabs may begin at any time of year. In geographic areas where mosquitoes and fleas are seasonal, the treatment schedule should begin one month prior to the expected onset and should continue until the end of "mosquito and flea season." In areas with year-round infestations, treatment should continue through the entire year without interruption.

Adverse Reactions

The following adverse reactions have been reported in dogs after giving milbemycin oxime or lufenuron: vomiting, depression/lethargy, pruritus, urticaria, diarrhea, anorexia, skin congestion, ataxia, convulsions, hypersalivation, and weakness.

To report suspected adverse drug events, contact Virbac at 1-800-338-3659. For additional information about adverse drug experience reporting for animal drugs, contact FDA at 1-888-FDA-VETS or

Mode of Action

Milbemycin oxime, one active ingredient in Sentinel Flavor Tabs, is a macrocyclic anthelmintic which is believed to act by interfering with invertebrate neurotransmission. Milbemycin oxime eliminates the tissue stage of heartworm larvae and the adult stage of hookworm (Ancylostoma caninum), roundworm (Toxocara canis and Toxascaris leonina) and whipworm (Trichuris vulpis) infestations when administered orally according to the recommended dosage schedule.

Lufenuron, the other active ingredient in Sentinel Flavor Tabs, is an insect development inhibitor which breaks the flea life cycle by inhibiting egg development. Lufenuron's mode of action is interference with chitin synthesis, polymerization and deposition. Lufenuron has no effect on the adult flea. After biting a lufenuron-treated dog, the female flea ingests a blood meal containing lufenuron which is subsequently deposited in her eggs. Lufenuron prevents most flea eggs from hatching or maturing into adults and thus prevents and controls flea populations by breaking the life cycle. (See Efficacy).


Sentinel Flavor Tabs are indicated for use in dogs and puppies, four weeks of age and older, and two pounds body weight or greater. Sentinel Flavor Tabs are also indicated for the prevention of heartworm disease caused by Dirofilaria immitis for the prevention and control of flea populations, the control of adult Ancylostoma caninum (hookworm), and the removal and control of adult Toxocara canis and Toxascaris leonina (roundworm) and Trichuris vulpis (whipworm) infections.

Lufenuron controls flea populations by preventing the development of flea eggs and does not kill adult fleas. Concurrent use of an adulticide product may be necessary for adequate control of adult fleas.

Without concurrent use of an adulticide, adequate flea control may not be achieved in dogs that have repeated exposure to flea infested animals or environments.


Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian.


Not for human use. Keep this and all drugs out of the reach of children.


Do not use in puppies less than four weeks of age and less than two pounds of body weight. Prior to administration of Sentinel Flavor Tabs, dogs should be tested for existing heartworm infections. Infected dogs should be treated to remove adult heartworms and microfilariae prior to initiating treatment with Sentinel Flavor Tabs. Mild, transient hypersensitivity reactions manifested as labored respiration, vomiting, salivation and lethargy have been noted in some treated dogs carrying a high number of circulating microfilariae. These reactions are presumably caused by release of protein from dead or dying microfilariae.

Sentinel Flavor Tabs immediately break the flea life cycle by inhibiting egg development. However, preexisting flea populations may continue to develop and emerge after treatment with Sentinel Flavor Tabs has begun. Based on results of clinical studies, this emergence generally occurs during the first 30-60 days. Therefore, noticeable control may not be observed until several weeks after dosing when a preexisting infestation is present. Cooler geographic areas may have longer lag periods due to a prolonged flea life cycle. The concurrent use of an approved adulticide may be employed depending on the severity of the infestation.

If a Sentinel Flavor Tabs-treated dog comes in contact with a flea-infested environment, adult fleas may infest the treated animal. These adult fleas are unable to produce viable offspring. The temporary use of an adulticide product may be necessary to kill these adult fleas.

Efficacy: Milbemycin Oxime

Milbemycin oxime provided complete protection against heartworm infection in both controlled laboratory and clinical trials.

In laboratory studies, a single dose of milbemycin oxime at 0.5 mg/kg was effective in removing roundworm, hookworm and whipworm. In well-controlled clinical trials, milbemycin oxime was also effective in removing roundworms and whipworms and in controlling hookworms.

Efficacy: Lufenuron

Lufenuron provided 99% control of flea egg development for 32 days following a single dose of lufenuron at 10 mg/ kg in studies using experimental flea infestations. In well-controlled clinical trials, when treatment with lufenuron tablets was initiated prior to the flea season, mean flea counts were lower in lufenuron-treated dogs versus placebo-treated dogs. After 6 monthly treatments, the mean number of fleas on lufenuron-treated dogs was approximately 4 compared to 230 on placebo-treated dogs.

When treatment was initiated during the flea season, lufenuron tablets were effective in controlling flea infestations on dogs that completed the study. The mean flea count per lufenuron-treated dog was approximately 74 prior to treatment but had decreased to 4 after six monthly doses of lufenuron. A topical adulticide was used in the first eight weeks of the study to kill the pre-existing adult fleas.

Safety: Milbemycin Oxime

Milbemycin oxime has been tested safely in over 75 different breeds of dogs, including collies, pregnant females, breeding males and females, and puppies over two weeks of age. In well-controlled clinical field studies 786 dogs completed treatment with milbemycin oxime. Milbemycin oxime was used safely in animals receiving frequently used veterinary products such as vaccines, anthelmintics, antibiotics, steroids, flea collars, shampoos and dips.

Two studies in heartworm-infected dogs were conducted which demonstrated mild, transient hypersensitivity reactions in treated dogs with high microfilaremia counts (see Precautions for reactions observed). Safety studies in pregnant dogs demonstrated that high doses (1.5 mg/kg = 3X)of milbemycin oxime given in an exaggerated dosing regimen (daily from mating through weaning), resulted in measurable concentrations of the drug in milk. Puppies nursing these females which received exaggerated dosing regimens demonstrated milbemycin-related effects. These effects were directly attributable to the exaggerated experimental dosing regimen. The product is normally intended for once-a-month administration only. Subsequent studies included using 3X daily from mating to one week before weaning and demonstrated no effects on the pregnant females or their litters. A second study where pregnant females were dosed once at 3X the monthly use rate either before, on the day of or shortly after whelping resulted in no effects on the puppies.

Some nursing puppies, at 2, 4, and 6 weeks of age, given greatly exaggerated oral doses of milbemycin oxime (9.6 mg/ kg = 19X) exhibited signs typified by tremors, vocalization and ataxia. These effects were all transient and puppies returned to normal within 24 to 48 hours. No effects were observed in puppies given the recommended dose of milbemycin oxime (0.5 mg/ kg). This product has not been tested in dogs less than 2.2 pounds in body weight.

A rising-dose safety study conducted in rough-coated collies manifested a clinical reaction consisting of ataxia, pyrexia and periodic recumbency in one of fourteen dogs treated with milbemycin oxime at 12.5 mg/kg (25X monthly use rate). Prior to receiving the 12.5 mg/kg dose (25X monthly use rate) on day 56 of the study, all animals had undergone an exaggerated dosing regimen consisting of 2.5 mg/kg milbemycin oxime (5X monthly use rate) on day 0, followed by 5.0 mg/kg (10X monthly use rate) on day 14 and 10.0 mg/kg (20X monthly use rate) on day 32. No adverse reactions were observed in any of the collies treated with this regimen up through the 10.0 mg/kg (20X monthly use rate) dose.

Safety: Lufenuron

Lufenuron tablets have been used and tested safely in over forty breeds of dogs, including pregnant females, breeding males and puppies over six weeks of age. In well-controlled clinical trials, 151 dogs completed treatment with lufenuron tablets. Lufenuron tablets were used safely in animals receiving frequently used veterinary products such as vaccines, anthelmintics, antibiotics and steroids. In a ten-month study, doses up to 10X the recommended dose rate of 10 mg/kg caused no overt toxicity. A single dose of 200 mg/kg (20X the recommended dose rate) had no marked effect on adult dogs, but caused decreased activity and appetite in eight week old puppies. Mean body weights of male and female puppies were higher in treated versus control group at the end of the study. In specifically designed target animal safety studies, lufenuron tablets were tested with concurrent administration of flea adulticides containing carbaryl, permethrin, chlorpyriphos and cythioate. No toxicity resulted from these combinations. Lufenuron tablets did not cause cholinesterase inhibition nor did they enhance cholinesterase inhibition caused by exposure to organophosphates.

Four reproductive safety studies were conducted in breeding dogs with lufenuron tablets: two laboratory and two well- controlled clinical studies. In one of the laboratory studies, where lufenuron was administered to beagle dogs at doses equivalent to 90X (3X daily) the monthly recommended dose of 10 mg/kg, the ratio of gravid females to females mated was 8/8 or 100% in the control group and 6/9 or 67% in the lufenuron-treated group. The mean number of pups per litter was two animals higher in the treated versus control groups and the mean birth weights of pups from treated bitches in this study was lower than control groups.

These pups grew at a similar rate to control pups. There was a higher incidence of four clinical signs in the lufenuron-treated versus control group: nasal discharge, pulmonary congestion, diarrhea/dehydration and sluggishness. The incidence of these signs was transient and decreasing by the end of lactation. Results from three additional reproductive safety studies, one laboratory and two clinical field studies evaluating eleven breeds of dogs, did not demonstrate any adverse findings for the reproductive parameters measured including fertility, pup birth weights and pup clinical signs after administration of lufenuron up to 5X the recommended monthly use rate.

Data from analysis of milk from lactating animals treated with lufenuron tablets at 2X and 6X the recommended monthly use rate demonstrates that lufenuron concentrates in the milk of these dogs. The average milk:blood concentration ratio was approximately 60 (i.e., 60X higher drug concentrations in the milk compared to drug levels in the blood of treated bitches). Nursing puppies averaged 8-9 times higher blood concentrations of lufenuron compared to their dams.


Give Sentinel exactly as directed by your 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 1 Flavor Tab every month (Brown Box), 11 to 25 pounds is 1 Flavor Tab every month (Green Box), 26 to 50 pounds is 1 Flavor Tab every month (Yellow Box) and 51 to 100 pounds is 1 Flavor Tab every month (White Box). For dogs over 100 pounds give the appropriate combination of tablets. To ensure adequate absorption, always administer Sentinel to dogs immediately after or in conjunction with a normal meal. 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 in a dry place at controlled room temperature, between 59-77F (15-25 C). 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.
Side effects of Sentinel are rare although some pets may exhibit vomiting, depression, drowsiness, itching, hives, loss of appetite, diarrhea, or seizures, hypersalivation, and weakness. If these or other symptoms develop contact your veterinarian.
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.
Tell your veterinarian if your pet has ever had an allergic reaction to the medication.
If a dose is missed and a 30-day interval between dosing is exceeded, administer Sentinel immediately and resume the monthly dosing schedule. If Sentinel replaces daily diethylcarbamazine (DEC) for heartworm prevention, the first dose must be given within 30 days after the last dose of DEC.
Contact your veterinarian immediately.
Because humans can contract hookworms and roundworms from pets, it is important to maintain good personal hygiene. It is also important to eliminate fleas on your pet and in the household.
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 your pet is also being given amiodarone (Cordarone), azole antifungals such as ketoconazole, carvedilol (Coreg), cyclosporine (Atopica), diltiazem (Cardizem), erythromycin (Ery-Tabs) or clarithromycin (Biaxin), quinidine, spironolactone (Aldactone), tamoxifen, and verapamil (Calan). Do not give Sentinel to your pet if already giving an alternate heartworm medication.
Both products protect dogs against heartworms, roundworms, and hookworms, but Sentinel Flavor Tabs also protect against 2 important and common parasites that Heartgard Plus doesn’t: fleas and whipworms.
In addition to providing flea and heartworm protection, you’ll also be protecting your dog against common intestinal parasites roundworms, hookworms, and whipworms.


Review Summary
98 Reviews
90% (88)
9% (9)
0% (0)
1% (1)
0% (0)
97% Recommend this product (95 of 98 responses)
By Bronte
Enid, ok
Great communication
June 7, 2015
Highly recommended seller and product! They made sure to stay in contact while waiting for my vet to respond. They were very fast and professional ! The product is great too my dog has been happy and healthy . This is by far the best price including shipping that I was able to find.
By Jim85254
Scottsdale, AZ
Great Product
September 14, 2021
Great Product and a great price. My girl's love their products. They are easy to eat and they love them. They are just the right size for them to eat. They love the taste and eat them right up.
By Carolyn
Lancaster, PA
Great product/great price
April 18, 2021
Been using Sentinel for years and with 4 different dogs now and love it!
Very easy process and this site had the best price!
By J W.
Clovis, California
Great service
February 28, 2021
Product was received quickly even after a glitch with my vets records. Very happy with the service.
By marc
great product
February 16, 2021
I love this once a month pill.. fast shipping and price..
By marc
lakeland fl
love this product
February 16, 2021
I love that this takes care of both fleas and heart worms.. no messy liquid on their neck.. just one pill once a month
By Lucie K.
Keep Heartworms and Fleas AWAY!
February 3, 2021
These heartworm/flea preventatives are the best!!
My pup before I adopted her had heartworms and the treatment for them - this was the best medicine to keep her safe in the future and has the added flea preventatives also! My vet is a Texas A&M graduate, which is a rugged way to become a vet - I trust her to keep my Molly safe!
By Victoria
Masontown pa
Great product and service
January 22, 2021
First time using this service since Chewy was out of stock. Great service and product.
By Christy K.
Great product
November 22, 2020
Great customer service experience
By Patricia F.
Sebastopol California
Flea and Heartgaurd control
October 25, 2020
We have been using Sentinel for many years and it does the job in 1 application each month !! It Works !! We love the Connivence all in one pill !!
By Linda R.
South Carolina
October 24, 2020
I have used Sentinel Flavor Tabs for all my pets forever. They work very well.
By Elizabeth
Hayward, ca
Sentinel for Dogs
October 1, 2020
Our dog will eat his medicine rolled up in a piece of lunch meat. He loves it.
By Dan
Philadelphia, PA
Vet Recommended
September 17, 2020
We've always used this because our vet recommends it. Never had any issues!
By Jeff
Hampton, Tennessee
Best price
May 24, 2020
Quick service, arrived earlier than expected. Cheapest price I could find.
  • Great price, works well.
  • No issues
By Joyce
Redlands, CA
Vet recommended, well priced and convenient
May 23, 2020
The vet was giving this to my dog but at a much higher price. I saved a lot of money buying online. And I didn’t have to pay for an office visit, which saved even more money and time. This is my second purchase and I plan to continue to buy from them. Everything goes smoothly or they make it right.
By wendy
north salem, new york
Vet recommended
May 17, 2020
This brand is more expensive than Frontline but Pet Smart offers great pricing and my dog is doing very well on the medicine
By Melodie
Minneapolis, MN
Great Deal
March 11, 2020
Trusted and great product for a great price!
  • Price
  • Quality
By DunPainted1
Plant City, FL
Great service, fast shipping
February 14, 2020
Will keep ordering !
By G-Mom
Austin, TX
Good Price - Fast Shipping.
February 10, 2020
Good Price and Fast Shipping. Thanks!
By Sheila
Crossville, TN
Good Price
February 8, 2020
Worked with me getting the ok from my vet and getting the pills to me in time..Thanks
By Louise
Wyomissing, PA
Safe heartworm medication
February 6, 2020
I have used Sentinel for 25 years for all 4 of my dachshunds and never had a reaction. Recently I got a mini doxie, who at adult weight is only 11.3 pounds, and the vet said even though he was on the low side of the Sentinel green (11-25 pounds), he still recommended the “green” because it is one of the safest on the market. Love the product; just have to be vigilant with remembering to give the pill. I always start them on the first of the month so it’s easy to remember!
  • Once a month oral tablet they can chew if you choose. Also, no mess since it’s a heartworm and flea medication.
  • Remembering to give the pill.
By Renee' K.
Best Heartworm Protection and Flea Population Prevention
January 24, 2020
I've been using this product for all the dogs in my life for over 20 years - most of which time I've lived in the heartworm rampant states of the Carolinas & Texas - and have never had a dog come up heartworm positive, or have I ever had a dog have a negative reaction or long-term effect from this medication.
It also does help to effectively prevent flea populations in dogs and the environments (indoor & outdoor) in which they live without the seizure and gastrointestinal side effects of the newer flea prevention oral medication pills. I actually researched this topic in detail & found that the active flea prevention ingredient in Sentinel has the best track record of pet safety over ALL the other oral meds on the market! BUT, it must be noted that the company is emphatic that the flea protection lasts only 32 days, and it takes UP TO SEVEN DAYS to become effective in the dog's system again if you let the 32 days lapse before readministering! So don't delay a dose, and do so EXACTLY @ the 30 day mark! -Or else you could be introducing flea populations to your dog & environment!! I did so once when we went on a 2 week trip, & I forgot my dog's monthly pill, so she was late in getting her dose by 5 days.... Never again will I do that! Apparently she picked up fleas @ a hotel on the way home, of which I wasn't aware of until I got home, so the fleas contaminated & repopulated not only my truck, but also my house & yard! It took me over a month to have a totally flea-free environment again, & I had to do a LOT of house cleaning in that time (to suck up & wash away untreated flea eggs & larvae), as well as I had to bomb my truck & spray my yard - which I do NOT like doing!
Anyway, I learned my lesson that if I'm traveling, just double-protect them with a good spot-on product, like Advantage II, AND DON'T FORGET TO TAKE THE NEXT MONTH's PILL WITH ME!! LOL
  • Extremely effective heartworm prevention with a long track record, and is the safest heartworm prevention and flea population protection product on the market today.
  • Must be readministered within no later than 32 days from previous dose to maintain continuous flea population prevention protection.
By Kathy
New Hampshire
January 23, 2020
My vet recommends this. My 2 dogs have taken it for years. No side effects.
By Leigh
Best prices,
January 19, 2020
I have 2 dogs and am always shopping for the best prices on heartworm pills. I purchase a years worth at a time for both and EntirelyPets has the best prices & fast and friendly service!
By Annie
Easy and effective
January 19, 2020
I’ve used Sentinel for years. The dogs love them. I just add it to their breakfast once a month and I’m done with heartworm prevention! Couldn’t be any easier,,
By Kenny
Bradenton, Florida
Excellent Pricing
December 22, 2019
The price for Sentinel was significantly less than the other sites I have purchased the product from. Delivery was timely and without delay!
By Karen
Corpus christi
December 4, 2019
I have been buying these from Petmeds for years thinking I was getting a good deal on the price. I saved $18.00 buying from Entirely Pets Pharmacy for the exact same product!! I am very happy with them!
  • Price!
  • None
By Dora R.
Norman, OK
Entirely Pets
November 27, 2019
Great prices and quick service!
By Gary
Best product ever.
November 20, 2019
Just 1 pill no messy oil on back works great
  • Just 1 pill no messy oil on back works great
By Gary
Best product ever
November 20, 2019
Just 1 pill no messy oil on back works great as usual
  • Just 1 pill no messy oil on back works great

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