hero banner

hero banner mobile

Sentinel Flavor Tabs for Dogs

By Sentinel
(1,470 reviews)
Veterinary Diet Item
Have an account?
Sign in to continue shopping

Usually shipped in 1-3 business days.* Learn more

Sentinel Flavor Tabs for Dogs

By Sentinel
$51.99
One-time purchase
$51.99 AutoShip
Availability:
  • In Stock

Prescription needed

We'll collect your vet's information at checkout to verify the prescription.

Have an account?
Sign in to continue shopping
Weight and Color:
Month Supply:
Weight and Color:
Month Supply:
This item requires vet authorizationWe’ll contact your vet clinic for you.
AutoShip & Save 0%

Sorry, there is a back order on this item

Usually shipped in 1-3 business days.* Learn more

Big Savings on Triple Protection!
Save up to 40% with AutoShip

$30 max savings.

Product Overview

Sentinel Flavor Tabs are administered monthly to prevent heartworm disease, control and prevent fleas, control adult hookworm, and control and remove adult roundworm and whipworm. It is appropriate for puppies and dogs aged four weeks or older and weighing 2 lbs or higher. See the Allivet Heartworm Comparison chart to find which heartworm prevention is best for your pet.

Sentinel heartworm prevention kills any immature heartworms your dogs may have been exposed to during the preceding month. It also treats intestinal infections of adult roundworms and hookworms. It does not kill adult fleas but does keep flea eggs from maturing to adulthood.

Formulated with a flavorful taste that most dogs like, Sentinel flavor tabs can be given as a treat and most dogs will easily accept the active ingredients. However, you can also offer them with food in the same way you would other tablets or pills. Whenever you administer Sentinel flavor tabs, your dog should also eat a full meal. Closely watch your dog to be sure they consume the entire dose. If they do not consume all of the dosage, give them another full recommended dose as soon as you can. Sentinel heartworm prevention should always be given with or immediately after a full meal to make sure it is fully absorbed by your dog and provide maximum protection.

Sentinel (milbemycin oxime/lufenuron) Flavor Tabs are chewable tablets manufactured by Merck that control flea populations and adult hookworms, and remove and control adult roundworm and whipworm infections in dogs and puppies. In addition Sentinel helps prevent heartworms.
For puppies and dogs ages 4 weeks and up, with a bodyweight of 2 lbs or greater. Sentinel is not safe to use in cats. Never give dog medications to cats and never give large dog tablets to small dogs. Some dog medications contain ingredients that are toxic to cats.
Sentinel is an oral monthly tablet with a savory beef flavor. It:
  • Protects against many types of infections and infestations
  • Controls existing flea infestations
  • Prevents and treats heartworms
  • Controls and treats roundworms and whipworms
  • Lufenuron and milbemycin oxime eradicate infestation of worms and control fleas
  • Milbemycin oxime, a macrocylic anthelmintic, is believed to interfere with invertebrate neurotransmission
  • Milbemycin oxime is known to eliminate heartworm larvae in the tissue stage, along with roundworm (Toxascaris leonina and Toxocara canis), whipworm (Trichuris vulpis), and hookworm (Ancyclostoma caninum) when the recommended dosage schedule is followed
  • Lufenuron is shown to controlfleas by preventing flea eggs from developing, but it does not kill fleas in the adult stage. An adulticide may be used concurrently to control adult fleas adequately.

The following side effects have been reported:

  • Diarrhea
  • Vomiting
  • Loss of appetite
  • Depression
  • Lethargy
  • Staggering
  • Drooling
  • Seizures

Sentinel® does not have any known reaction with other drugs at this time.

Studies have indicated that collies, sheepdogs, and other herding dog breeds that have a genetic mutation known as MDR1 may be more sensitive to elevated levels of milbemycin and more likely to have serious adverse reactions including coma and death. These adverse reactions are associated with high quantities of milbemycin. Discuss any concerns you have with your veterinarian. Some forms of milbemycin that contain pork extracts for flavor may cause a food allergy in some pets.

Your pet should be tested for heartworms before using Sentinel heartworm preventive, as pets with high levels of heartworms in their system sometimes react to milbemycin. Discuss the use of Sentinel for pregnant or lactating dogs with your veterinarian.

Milbemycin Oxime - Lufenuron
Contact your closest emergency pet hospital.
  • Sentinel should not be given to puppies under 4 weeks old or under 2 pounds.
  • Your dog should be tested for heartworms prior to taking Sentinel.
Sentinel is sold in four tablet sizes in color-coded packages for oral administration to dogs and puppies according to their weight (see How to Use). Each tablet is formulated to provide a minimum of 0.23 mg/pound (0.5 mg/kg) of milbemycin oxime and 4.55 mg/pound (10 mg/kg) body weight of lufenuron.
Merck Animal Health


Pharmacists are standing by to offer Pet Parent counseling regarding prescription medication purchased from Allivet before and after dispensing. Pharmacists on duty are available Monday-Friday, 9:30AM - 5:30PM EST and will be on call Saturday 12:00PM - 4:00PM EST for consultation.

Before starting Sentinel flavor tabs, speak with your veterinarian about any other drugs your dog is taking, including vitamins and supplements. In addition, notify your veterinarian of any allergies or reactions they may have had to other medications. They will be able to answer all your questions about how Sentinel works, any possible adverse reactions, and any side effects to watch out for.

Intestinal parasites like roundworms and hookworms can be spread from pets to people. Discuss with your veterinarian additional measures you can take to help keep your pet from picking up intestinal worms, and how to protect your family and yourself.

To ensure adequate absorption, always administer SENTINEL FLAVOR TABS to dogs immediately after or in conjunction with a normal meal.

SENTINEL FLAVOR TABS have no effect on adult fleas, but control flea population by breaking the flea cycle at the egg stage. 

Treatment may begin at any time of the year. In geographic areas where fleas and mosquitos are seasonal, treatment should begin several weeks prior to the expected onset and should continue until the end of the flea and mosquito season. In areas with year-round infestations, treatment should continue the entire year without interruption.

It is important to treat all dogs in the household for fleas. Cats in the same household should be treated with approved products like lufenuron. 

SENTINEL FLAVOR TABS must be administered monthly, preferably on the same date each month. 

If you have any questions concerning the use of this product contact your veterinarian, who is your pet's healthcare expert. 

For technical assistance call 1-800-224-5318. SentinelPet.com  

Dosage :
Weigh your dog prior to administration to ensure proper dosage. Do not administer to dogs under 2 pounds or less than 4 weeks of age. Administer with a normal meal.

Recommended Dosage Schedule: 
Dog’s Weight  /  Milbemycin Oxime Per Tablet  /  Lufenuron Per Tablet
2 to 10 lbs.    /                  2.3 mg                   /                46 mg
11 to 25 lbs. /                   5.75 mg                 /               115 mg
26 to 50 lbs. /                  11.5 mg                 /                230 mg
51 to 100 lbs. /                23 mg                   /                 460 mg
 
For dogs over 100 pounds give the appropriate combination of tablets.
The active ingredients present in Sentinel Flavor Tabs are milbemycin oxime and lufenuron.

About This Product

Customer Reviews

4.9
1,470 reviews
5 1352
4 74
3 15
2 15
1 15
Customer review photo
Julie W Verified Purchase
August 8, 2026

Sentinel

My oldest dog has been on these tablets her whole life. We appreciate they way they keep her healthy

Mark F Verified Purchase
November 30, 2025

I’ve been using this heart worm tablet for many years with all my dogs. Never had a problem due to giving it to them every month.

Thomas S Verified Purchase
August 1, 2025

Sentinel Heartworm Tablets

My German Shepard, Bella, has been taking Sentinel Heartworm Tablets for several years. She readily chews the tablet when I offer it to her, and she has had no issues with heartworms.

Alka A Verified Purchase
June 21, 2025

Great Heartworm Tablet

My dog loved it , never had any issue with heartworm , he is using it since he was 6months old, he is 7yrs. old now , very healthy dog.

Carinda P Verified Purchase
June 9, 2025

Have been using Sentinel Heartworm Tabs for Many Years !!!

I have been using Sentinel Heartwork Flavor Tablets for Dogs (oral tabs) for many years. I buy them from Allivet. I am very pleased with both the product and the service I received from Allivet.

Mary L Verified Purchase
May 29, 2025

Dogs love the taste!

I’ve had no problems and the dogs tolerate this medication very well. I am a breeder, and I trust Sentinel based on repro vets’ recommendations. Fast delivery, as well, and excellent customer service!

Will R Verified Purchase
October 8, 2024

Works well. My dog never has had any reactions to this drug. He has also never gotten fleas or worms since taking this combo pill.

Marvia K Verified Purchase
March 5, 2024

Piper is very picky when it comes to ingesting anything. Sentinel tablets are very small and easily disguised in a small piece of cheese.

Shelley H Verified Purchase
February 26, 2024

My dog loves these chewable tablets! I just put one in with his food once a month and he eats it right up! In many years of using these tablets I've never had one flea and we are in a vacant lot with grass every day.

Melissa R Verified Purchase
November 18, 2023

My dogs loves Sentinel. They take them like a treat. No forcing or hiding pill in something. Highly recommended this product.

Shirley G Verified Purchase
June 19, 2023

I have been using Sentinel for my dogs for years. What attracted me to use it for my dogs is that does two jobs with one montly pill. Sentinel is an antiparasite product AND dewormer. It control flea eggs and larvae, which prevents a flea population explosion later. More importantly Sentinel also kills heartworm larvae, which means it protects against eartworm infection. In addition, it gets rid of some other intestinal worms such as roundworms, whipworms, and hookworms. We live in North Idaho and have deer traipsing daily through our yard. They leave behind their droppings and probably ticks, but my dogs have never gotten ticks or fleas since being on this product. And, because my beagle likes to eat deer droppings, I feel confident that she is protected against most other worms found in their stool.

Edilberto C Verified Purchase
June 18, 2023

Has worked well with all my dogs for years. No heartworms or fleas.

Jaleel D Verified Purchase
April 24, 2023

these work the best for our pet. he loves them and it comes in 6 month to 12 month option

Meghan
January 4, 2023

Great price! It's small so my dog takes it easily!

Colleen W
December 14, 2022

All my vet supplies right at my finger tip! Great service and quality products.

HBW
November 29, 2022

We have always used Sentinel for both of our pups & never had any issues. Also Allivet's Autoship program makes it fast & effortless to get the medication when we need it & they even contact the vet for you to get the prescription.

Nadia
November 2, 2022

We are using sentinel for many years. Never had problems with it. Allivet has great customer service and fast delivery

Maria
November 2, 2022

I have give this medication to my dear Max our Golden Retriever and 6 years and he is healthy and always pass his blood test free of warms. Also the convenience of the system that

Nicolette
October 3, 2022

Allivet always has the best price and speedy delivery...I would certainly recommend! I recently ordered 2 brown packs (1 year total supply) of the Sentinel when Allivet e-mailed me a great coupon code....delivered so quickly after they verified my veterinarian's approval for this Rx. I have always given my 6-yr old, 8.5-lb fur-baby this Sentinel each month since she was a puppy, as recommended by my vet....I just hide it in a ball of chunky PB for dogs (peanuts only - no sugar, salt, xylitol, etc.), which she loves to scarf down, and she has always been in great health (negative heartworm tests & no fleas ever)!

A M
October 1, 2022

Very happy with Sentinel for our dogs. We've used this for years (dogs are 10 yrs and 7 yrs). The product has been wonderful and Allivet always ships it quickly, working with our vet when we need a refill on the prescription. Thanks for helping us take good care of our dogs' health!

Aretha S Verified Purchase
September 30, 2022

It works great for my dog

Mary F Verified Purchase
August 27, 2022

This always works for my dogs

Elena H
May 9, 2022

My dogs have been on Sentinel monthly for almost two years and now suddenly we have a flea infestation. All were just checked for heartworms and that was negative so it obviously works for heartworms but fleas.

Cynthia C Verified Purchase
February 14, 2022

GREAT PRICE - COULDN'T FIND ANYONE ELSE LOWER

Mary M Verified Purchase
February 3, 2022

I like that it covers heartworm and offers some flea protection

Jimmy D Verified Purchase
January 26, 2022

Works well so we stick with it for over 9 years with our Chiweenie.

Carol J Verified Purchase
January 25, 2022

Heartworm, flea, and tick prevention

Patricia J Verified Purchase
January 25, 2022

Have used this product for years. Allivet is wonderful and very easy to use.

Jean L Verified Purchase
January 25, 2022

My dog has been using it for the last 16 years and it seems to work well and she feels good using it.

Clay J Verified Purchase
January 25, 2022

My Cocker is often out on a golf course where I've seen opossums, racoons and bears. I haven't had any worm problem in the 3 years here.

Susan S Verified Purchase
January 25, 2022

Best price, took coupons too

John L Verified Purchase
January 25, 2022

This is the best deal online

Hristos L Verified Purchase
January 25, 2022

the best product my vet recommends to prevent heartworm

Mary B Verified Purchase
January 25, 2022

I use Allivet for both prescriptions for our dog. I am on automatic refill and it works wonderfully. Been using this company for several years. Great!

Barbara D Verified Purchase
November 11, 2021

reasonably price, quick service, never had issue that was not resolved promptly

Janet P Verified Purchase
November 8, 2021

Have used Sentinel for all my collies and never had a problem with heart worm or any negative reaction or side effects. I trust this medication for my collies

Harry B Verified Purchase
November 3, 2021

Vet recommended and your price is better than vet.

Elda L Verified Purchase
October 27, 2021

My pet is been taken sentinel for several years. I've been happy with results of this med.

Mary E Verified Purchase
October 15, 2021

Perfect for my pups. Been staying very healthy. Prices are great.

Genevieve F Verified Purchase
October 7, 2021

Works pretty well.

Janan B Verified Purchase
October 5, 2021

My dog likes the taste of these and willingly eats them. She would not eat another product we tried.

Johnny D Verified Purchase
September 28, 2021

My dog has been taking Sentinel Heart Worm meds for 6 1/2 years and has never had any bad reactions. His only problem is that he refuses to eat a hard pill, so I put peanut butter on it and the pill and he takes it without ay problems. On my latest order, the Post Office somehow lost my order. Upon contacting Allivet and informing them about the problem, they sent me a free replacement order after checking the tracking details. This was unexpected and shows that not only did I get the best product price, but I also choose the best company to fill my order.

Virginia G Verified Purchase
September 23, 2021

Always get good and immediate service

Roberto a Verified Purchase
September 15, 2021

It has all the protection my puppy need to keep him healthy

Roanna G Verified Purchase
August 30, 2021

Best prices and quick shipping

Denise L Verified Purchase
August 27, 2021

Took awhile, but no fleas on my property. Works great for the wild cats outside. Put in wet cat food for them. Really cured the flea problem. Works on my dogs.

Michelle E Verified Purchase
August 24, 2021

Excellent service always!

Napoleon B Verified Purchase
August 23, 2021

Great double product it controls fleas and prevents heartworms.

Kimberely P Verified Purchase
August 19, 2021

Works great!

Kathy M Verified Purchase
August 13, 2021

Great price

Bonnie l Verified Purchase
August 5, 2021

better pricing than at the vet's office

Wanda r Verified Purchase
August 3, 2021

Loves it

Alma G Verified Purchase
July 16, 2021

It works and no oily residue on my dog.

Kathryn R Verified Purchase
July 12, 2021

Safe and effective

John R Verified Purchase
July 12, 2021

I have been using it for years, really protects my fur baby's

Darcy W Verified Purchase
July 8, 2021

This works pretty good.

Michael G Verified Purchase
June 28, 2021

Works!

Ramona M Verified Purchase
June 28, 2021

Excellent product-no fleas in my house!

Faith P Verified Purchase
June 14, 2021

Its a shame, I tried Sentinel because I listened to all the good reviews and the great price. Sentinel does not work. My maltipoo mix was itching nonstop even on this pill. I'd find fleas on him often. I got my home exterminated but my dog gets new ones that jump on him while on his walks. I purchased a year's supply and I have already decided to switch after 5 months. My poor baby didn't get any break from those fleas while on Sentinel.

Oscar A Verified Purchase
June 14, 2021

Quick service, good prices.

William Q Verified Purchase
June 8, 2021

Have been using SENTINEL, for more than 20 years, no issues.

BARRY M Verified Purchase
June 8, 2021

Great value

Theresa g Verified Purchase
June 8, 2021

Allivet is great with my orders and is always on time and great for my dogs too. Also provides great prices.

Shelley G Verified Purchase
May 26, 2021

Easy! Price could be lower for comparison

Karen M Verified Purchase
May 25, 2021

I've used this before and it works well!

Richard J Verified Purchase
May 25, 2021

best ever product but the price is not good it has gone up $30 more from last yr that is a big just

Andy R Verified Purchase
May 20, 2021

Top quality, great customer service, lowest price, quick delivery. What's not to like.

Dana M Verified Purchase
May 16, 2021

Best flea med with heart worm protection plus it's chewable. Dogs actually eat it!

William K Verified Purchase
May 13, 2021

Great company

Wendelyn O Verified Purchase
May 10, 2021

Works well

Del M Verified Purchase
May 10, 2021

Fast and secure way of purchasing your pet supplies.

Loren z Verified Purchase
May 3, 2021

best price, easy to use service!

Aarika T Verified Purchase
May 3, 2021

Easy, friendly website

Rick P Verified Purchase
May 3, 2021

Cheaper than buying at the Vet

Elissa F Verified Purchase
May 3, 2021

Has worked for 15 years for my K C

Linda H Verified Purchase
May 3, 2021

Cheaper than vet prices and free shipping.

Delilah P Verified Purchase
May 3, 2021

Nice service

Kathleen W Verified Purchase
May 3, 2021

Best price online!!

Sophie P Verified Purchase
May 3, 2021

Cheaper than any place else.

Olga F Verified Purchase
May 3, 2021

It is effective and no side effects

STEPHEN M Verified Purchase
May 3, 2021

makes things easer

Kathleen C Verified Purchase
May 3, 2021

Excellent price

Chelsea S Verified Purchase
May 3, 2021

Love this! It's affordable and convenient!

Sue R Verified Purchase
May 3, 2021

The price was much more affordable, ordering was simple, shipping was on time and I am very pleased with the customer service.

Lottie J Verified Purchase
May 3, 2021

It really works

Edward M Verified Purchase
May 3, 2021

Cheaper than HeartGuard plus adds flea and tick protection.

Debra P Verified Purchase
May 3, 2021

Easy to place order and wili have it shipped to home.

Kathleen S Verified Purchase
May 3, 2021

I chose sentinel because it is easy to administer

Nancy J Verified Purchase
May 3, 2021

Love this product

Gary H Verified Purchase
May 3, 2021

saved a huge amout of money

Toni C Verified Purchase
May 3, 2021

I love that it covers heartworms, fleas, and intestinal worms

Charlene B Verified Purchase
May 3, 2021

Less expensive than from my vet

Rose M Verified Purchase
May 3, 2021

I know there are lots of newer options and some even have tick prevention. I stick with Sentinel because not only does it work-it causes no discernable side affects. That has not been the case with other products tried in the past. Added bonus is its less expensive than other products. I get my dogs the lyme disease vaccine so I'm not concerned that it doesn' t protect against ticks.

JANIE A Verified Purchase
May 3, 2021

Works for my pets

Tammy J Verified Purchase
May 3, 2021

it works

John T Verified Purchase
May 3, 2021

perfect for my little dog Fiona

Gary H Verified Purchase
May 3, 2021

free shipping

Margaret T Verified Purchase
May 3, 2021

It is a product we've used, for our dog, in the past. It works in keeping her healthy so why change?

Jennifer W Verified Purchase
May 3, 2021

Has worked well for our pet. Will continue to use....

Vinny D Verified Purchase
May 3, 2021

Sentinel 11 - 25 lbs 12 Month Supply Green

Questions & Answers