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At a Glance
Prevents heartworm & kills flea eggs in dogs
Delicious beef flavor
Kills flea eggs and prevents infestation
No messy pipette application
This product requires a prescription.

Sentinel for Dogs

Our Price

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Pet Size
Don't know your pet's weight?
If you can't get them on the scale, try this super simple method:

1) Weigh yourself.
2) Weigh yourself holding your pet.
3)Subtract the two numbers to get their weight.

Too heavy to hold? Your vet will weigh them if you ask (or may already have it on file if you call).
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How To Order Prescriptions Online

  • 1

    Find the right product

    Make sure it matches your pets prescription. Don't forget to compare the dosage for pills/capsules!

  • 2

    Add to Cart

    Just like any other online store. Make sure the quantity matches what's been prescribed by your veterinarian.

  • 3

    Tell us about your pet and vet

    Answer some questions during checkout and we'll contact your vet and verify the prescription for you. (you can also mail us the written prescription)

  • 4

    That's It!

    If the prescription has any refills, processing your future orders for that medication can be expedited.

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Rated 4.5 out of 5 by 185 reviewers.

  • Good for my pup!
    She thinks that she is a treat while taking this medicine. She says she wants more of this. by on 01/09/2019
  • Great Prices
    One pill does all great to use and dogs love it. by on 12/29/2018
  • flea meds work
    use them. otherwise you will have a house of fleas... by on 11/06/2018
  • My dog never had fleas, until I switched to Sentinel
    I had been using Trifexis on all of my dogs. For the past few months, I've been using Sentinel instead, since Trifexis is just not in my budget. While I can't tell a difference on my two black dogs, my white dog has been having visible fleas all the time. Since Sentinel only kills flea's eggs and not adult fleas, we started having a flea issue in the house for the first time, since we've had these dogs. We live a warm state with long, warm summers and fall, so I'm thinking Sentinel isn't going to cut it for us. by on 10/09/2018
  • Does the job
    My pupper finds this pill easiest to eat, and does not throw it up later like others we have tried. by on 08/27/2018
  • Sentinel works great!!
    I take my dog to the dog beach and dog parks so he is exposed to many parasites but he remains parasite free. Sentinel works great! by on 08/11/2018
  • great product
    my dog takes this without difficulty. easy to give and very effective! by on 08/08/2018
  • Sentinal
    You have to presume it will work. by on 07/17/2018
  • Sentinel..Is A Big No No
    I've been using Comfortis and Trifexis for years and never had an issue. I decided to save a few dollars by switching to Sentinel, since it was compared to Trifexis...worst mistake ever. Seems like the fleas are attracted to my dog even more. I will never buy this stuff again. Will be switching back to what I know works. Comfortis or Trifexis. by on 07/03/2018
  • Sentinel Works for Fleas
    I have been using Sentinel for years for my pugs and have not had any problems with fleas. Two years ago I switched to Seresto flea collar that was suppose to work for 8 months and within 5 months all my dogs had fleas. I have switched back to Sentinel and also use Frontline Plus during the summer months. by on 06/08/2018
  • So Easy and Convenient
    Purchased my heartworm meds for my 5 Chihuahuas from PetCare RX. The service is perfect for me. Easy order, they contact my vet for approval, great communications regarding status of my orders. Love that I can pay with Paypal! Will continue to use this petmed pharmacy! Thank you PetCareRX!! by on 05/26/2018
  • does its job
    so far works well for my dog, no fleas or ticks despite walking and running in wooded areas. by on 05/14/2018
  • Awesome
    Nothing bad to say about this product. Ive been using it since my boys were puppies. by on 05/10/2018
  • Sentinel
    I have been using Sentinel for two years , Its effective and Max doesn't mind it. I break it in half and he chews the tablet. I used to have a terrible time with Trifexis for my previous pup, a German Shepherd . Horrible taste and smell. by on 05/08/2018
  • great protection
    Sentinal is great for flea and heart worm protection. My dog has been on this for over a year now, and just had vet visit and negative for heart worm. this medicine has proven it works, no fleas ever. by on 04/20/2018
  • New Product
    I like 2 in 1..Heartworm and Fleas by on 03/28/2018
  • Sentinel for Dogs
    We have used this for years for our dog. She likes the chewable tablet and it has been very effective. by on 03/25/2018
  • Always Senintel...
    ...for all our dogs going back decades! by on 02/22/2018
  • Great for all 4 dogs we have
    So nice with long hair dogs (4 of them) to do an oral pill for everything vs topical. Easy to remember to give once a month. No fleas in our house with them all on the meds. by on 01/31/2018
  • Great for medication sensitive Dog's.
    So far so good. Been using this for years. This is much more tolerable for Dog's with heart-worm, etc. med. sensitivity's which my Dog has. by on 12/20/2017
  • Easy Treatment
    We've been using Sentinel for our dog, Boone, for the aspt four years and it works well. Boone eats it without a problem. All annual heartworm tests have been negative so the product works. by on 07/02/2016
  • Awesome Customer Service
    Great for your Pet and I thank Petcarerx for the great customer service every time I do an order! by on 07/01/2016
  • Very effective, no side effects.
    we've used this product for many years, very satified. GREAT price. by on 07/01/2016
  • Fast shipping, good price for a heartworm preventative
    We have been using Sentinel for a few years now and PetRx saved us quite a bit this year. This keeps our dogs healthy and heartworm free and is incredibly convenient to order online with renewal with the PetPlus program. My dogs eat this like a treat - no bread or peanut butter or anything like that needed. They have been flea-free their whole lives so I don't know if that is our yard being well kept or if it is due to the Sentinel. Same for heartworm - this monthly treatment appears to have kept them healthy. They have no side effects whatsoever when taking this product. This product - even though some think it takes care of Ticks, it does not. If you want tick prevention, you have to get another product. Our veterinarian also explained that it does not kill adult fleas, it only kills flea eggs and prevents them growing on the dog in the fur, so if you have outdoor pets or they run in unmowed fields, etc, you might want something that keeps the adult fleas off of them as well. But for us, this is all we need. PetRx delivered this to us fast and with no hassles. Thanks! by on 06/23/2016
  • Using Sentinel for years with excellent results.
    We are very happy with this product. Been using Sentinel for many years for our dog. by on 06/10/2016
  • Not effective for my pets
    I don't think this product had enough ingredients to keep fleas from attacking my two dogs. We fed them the products per the directions. We've since requested and are still waiting to receive a dose of Capstar to see if that can improve their condition. by on 05/26/2016
  • Worry free for another year
    When we bought our home we discovered that a previous owner had lost a dog due to Heartworm. We sure do not want to repeat that loss...so have to be diligent about a preventative. Sentinel is perfect for that and PetCare had by far the best price! by on 05/26/2016
  • Great product
    Great product as it combines flea and heartworm into one pill. However, my dog does not like these and I have to give it to her with some peanut butter. This has not been an issue with other pills. by on 05/02/2016
  • this product works really good
    the prices are excellent and the product works great! by on 03/28/2016
  • outstanding
    I have been using this product for about 3 years. He is 9 years old and is running around like a puppy. Love this product! by on 02/05/2016
  • Does not kill adult fleas
    I would not recommend this to anyone who thinks their dog might come into contact with fleas. This product does nothing to fend against adult fleas so you will have to invest in other products to treat them. It is cheaper for now a very apparent reason... by on 01/25/2016
  • Great product have used it for years
    I got everything I was promised price delivery 100% what I wanted great company thank you so much by on 12/25/2015
  • Great Heartworm Preventive
    Loves this because it also has a flea repellent so in fall/winter we can skip the Frontline with no worries of any fleas! by on 12/22/2015
  • Great doing businees with you.
    You communicated with the vet to get the prescription, sent the prescription quickly, and made the whole transaction very easy. I enjoy working with you. by on 12/16/2015
  • Keeps away the bugs.
    I have been giving this to my dogs for about 3 years. Every time the heartworm test comes due, the veterinarian has yet to find any critters in my dogs blood. It is doing exactly what I would hope it would do. by on 11/23/2015
  • No fleas!
    We were using Comfortis but a friend recommended Sentinel instead. When we learned that Sentinel was cheaper than Comfortis, we were interested. But the fact that it not only took care of fleas & ticks but also worms, we were sold. We have not had one flea since beginning the treatment! by on 11/08/2015
  • Sentinel Rocks
    I have been giving all three of my dogs Sentinel for years. It is an affordable, convenient & effective product. I highly recommend it. by on 11/06/2015
  • Sentinel
    The company was fine. They contacted my vet, process was easy. The bad part is now I'm getting email daily....annoying. when I want to buy more, I'll let you know. by on 10/19/2015
  • Excellent Product
    This is an excellent product and the only one that does not upset my dogs stomach, give it a try you will not be disapointed. Ask your vet! by on 10/17/2015
  • good product excellent price
    just started sentinel to early to tell effectiveness.Everything else about transaction was excellent by on 09/26/2015
  • Sentinel
    We are happy with the Sentinel product. We used to use another brand, without good results. Sentinel works for our dog? by on 09/17/2015
  • Great Product
    I have always liked this product. It works well and is easy to use. And the dog likes it! by on 08/10/2015
  • Happy
    I have been using this product for many years and have always been happy with it. by on 07/25/2015
  • Great effective product
    Easy to dispense to your pet. Double flea and tick protection when given with food, when also using a flea and tick med. highly recommend this product. by on 07/06/2015
  • Best for our dog
    So glad to have Sentinel back on the market. It has been a long time waiting. Our oldest dog who is 10 was on it since his birth. All of our past dogs and present it seems this is the only easy pill to give and works wonders with no problems. No side affects and no worries. We started using this pill back while we lived in NJ and now in Texas. by on 07/04/2015
  • Worked for my allergic to bug bite dog
    this pill works. It significantly helped my yorkie not get bitten from all the bugs in Florida, where we live. He never scratches air bites his skin anymore. Changed our lives.Highly recommended. by on 06/10/2015
  • Excellent
    We have 4 scotties-the sentinel is well tolerated! No side effects---which we had with another well known comparable product by on 06/08/2015
  • Wonderful product!
    I have used Sentinel on every dog I have owned and never have had a flea or heartworm problem. I have used this product for over 10 years and absolutely love it!!! One pill a month and you are done! by on 05/22/2015
  • Good all over product
    I purchased this product for simplicity and ease of use. My dog likes the tablet and it covers all kinds of parasites I want to protect my pet against. by on 04/23/2015
  • Same product for less
    I like that you can purchase the same medication from Pet Care Rx that you can get from your vey but at a cheaper price! by on 04/10/2015
  • Love the product!
    First of all I have to say to those giving a low rating because you can't get your dog to eat it put it in some food. We are rating the effectiveness not how well you can handle your dog! This stuff is great I saved so much money on buying flea prevention separately. My white dog always had an ugly grease mark from the topical and she likes to swim so it never worked for long now just an easy pill that anyone with a brain can administer and we are good to go! by on 04/09/2015
  • my dog loves this medicine
    My dog takes this little pill very easy and eagerly. Works well for fleas. Wish it worked for tick's too but have to buy something else for that. by on 03/23/2015
  • great product
    product not received from pet rx, the product works great for the past year by on 03/07/2015
  • Sentinel one per month and no worries
    I have been using Sentinel for my two dogs for six years now. There is a huge problem with Heartworm in Texas and although my dogs mostly stay inside, there is no skimping on the protection that I give them. They are my babies and thus, Sentinel is given to protect them from Heartworm, fleas, and other parasites. I give one to each once a month on the same day and I do not need to worry for the remainder of the month about whether or not they are safe. by on 02/20/2015
  • sental
    very good for my dog service is always great mailing is good I have no complaints at all by on 02/18/2015
  • Good combination medication
    I wish this would kill the fleas that may already be on the animal. I had to use a topical just in case they had fleas already. I do like the combination heartworm, flea, and other worm prevention. You just need to make sure the animal DOES NOT have fleas as it will not kill the ones already on the dog! by on 01/16/2015
  • Not Sure Yet
    Two weeks ago was the first time we gave to our dog, Mandi. Mandi spit that sucker right out and we knew it was fight time... we put it in her mouth again and she seemed to be eating it but she was faking us out. Then we broke into pieces and wrapped them in some ham slices...she ate the ham but found the Sentinel. So then, we did what any good parents would do... I held her and my husband shoved whatever was left down her little throat. I can't wait until next month.As for effectiveness, she doesn't have fleas so I guess it works. by on 12/20/2014
  • Love this site.
    I used to pay $150 mo for my pets flea and heartworm. Until i found PetCareRx. Now i pay less than half that. Shipping takes a little bit so i recommend ordering early to keep in the cycle. Other than that, I'll never buy their meds anywhere else. by on 12/08/2014
  • Great product!
    easy to administer and keeps my dogs flea free for a month at a time. works on my big 'outside' dogs and my little buddies. We live near the beach and fleas are a nightmare with the warm humidity and sand. playing in the water makes the topical flea control useless. by on 12/01/2014
  • came on time and good price
    Good product, good price, delivery was on time, thanks by on 11/20/2014
  • This product has great features
    I would recommend this product. It's easy to use and very convenient. by on 11/06/2014
  • Sentinel tabs
    Well, my dog has been given these all his life and the vet couldn't get them anymore, I don't remember why.I just place the tablet in a spoon of peanut butter, easy dosing because there is nothing my dog likes better than peanut butter. by on 11/04/2014
  • Hard to give to dog and still itching
    I found the tablets hard to give to my dog. I thought flavor tab would mean it would be flavorful to dog. but no, I finally crushed tablet and bought wet food and mixed it in the wet food for dog to get it. Not sure if crushing it was ok. Also, dog is still scratching, from fleas? I don't know. so not sure if the flea part works good. by on 10/28/2014
  • Good product
    We have used Sentinal for several dogs over several years, and we've always been pleased with it. The current dog takes it buried in peanut butter and gobbles it down. by on 10/16/2014
  • easy to use
    our dog hated the liquid drops to control fleas and ticks. he takes this like its food no worries about fleas or ticks and does not run away for monthly dose. dog how runs to you to take dose because of the good taste. by on 10/09/2014
  • Super easy
    One pill. Once a month. It's that easy. No liquids. No mess. by on 10/08/2014
  • Good product
    I choose to use this product for my dogs, because it doesn't make them sick or itch. The last heart worm medicine I used would make them sick and scratch like crazy. This one does not do that. by on 09/15/2014
  • Product came as promised
    So far my dogs have not had any fleas. I believe this product works good. My service and price was very good from PetCareRx.com. by on 07/28/2014
  • Affordable and Effective
    Much cheaper than heartguard and also protects against whipworms. by on 07/23/2014
  • Dogs love it
    Dogs love it so it easy to give them their "treats" for heartworm & other parasite prevention. by on 07/11/2014
  • Good value
    Sentinel is easy to use. My dog eats quite readily. I use it because it controls both worms and fleas. The price is reasonable compared to other combined worm and flea products. It does not kill fleas, it only prevents the eggs from hatching. I use another product to kill the fleas. by on 06/23/2014
  • Great price!
    Heartworm preventative is an expensive part of pet ownership. I shopped around and got the best price from PetCareRx. by on 06/22/2014
  • Love this stuff
    I used this for years and then my vet changed the dogs to Trifexis. My dogs hated it! They spit it out 2 and 3 times, and I mean from way down their throats!! There has never been an issue with the Sentinel, they will even eat it out of my hand if I forget to put it in their bowl with the food. It has been effective for heartworm and fleas for all of our dogs. by on 06/19/2014
  • Good Product
    My vet prescribed this for my dogs a couple of years ago. Since I have been buying these from PetCareRx, my savings have been substantial over what the vet charged. by on 06/06/2014
  • No more 2 meds every month
    finally I can give my 2 small dogs 1 pill a month that covers heart worms and the fleas etc. Trying to find the spot between their shoulder blades for the fleas etc. meds has been awful. They're happy campers and so is Mom :-) Thanks a lot! by on 05/15/2014
  • Not a flea/tick preventative!
    Geez people do some reading. Sentinel doesn't prevent flea or tick infestations. It interrupts the flea life cycle by preventing the development of flea eggs. Adult fleas and ticks will still get on your dog. Sentinel is primarily a heartworm, hookworm, roundworm, and whipworm preventative. It is also the safest heartworm med for the herding breeds that may have MDR1 gene mutation issues. by on 05/11/2014
  • This product does not work
    I have two dogs. We gave them this medication three weeks ago. While taking them for a walk, we get home and they have two fleas on them? My puppy has thicker fur and tends to attract the fleas more then the other one. Not only was it hard to give her the tablet, she kept spitting it out so we have to use a pill pocket, but it did not work. I paid all this money for yet another unsatisfied product! by on 05/06/2014
  • So glad they are available again
    I used Sentinel from the start when I got my Shep-Colli-Lab mix 8 yrs ago and had no problems at all. Then they put the hold on the manufacturer for another product and I was forced to switch to another product which was way more costly and did not keep the fleas at bay. I had to first take care of the flea problem that then developed in my house (another expense) and then switch to another product. I was thrilled to see they started selling it again. Great value, easy to use and it works!Radio by on 05/04/2014
  • Good heartworm medicine
    This product was not available for some reason. I used Trifexas in the meantime - it is wonderful that it is back since it quite a bit cheaper and the dogs take it well - in fact my collie takes it better (the Sentinel). by on 04/22/2014
  • very effective
    very effective, less money than other brands, dog tolerates the medication well, dog heartworm test negative. difficult to find a heartworm chewable for dogs under ten lbs. This med works for both of our dogs. by on 04/14/2014
  • I like that it takes care of more than one issue at a time!
    I have only given her the 1st dose, we live in Florida, the flea part of has not worked well yet, hopefully the 2nd dose works better. It would not be fair to say it does not work, not yet! by on 03/31/2014
  • Like once a month dosing and that it covers two areas in one pill.
    Our vet introduced us to this product and we like how it attacks two things in one pill and you give it once a month. One less medicine to keep up with. by on 03/23/2014
  • Need crushed pill method!
    My little Chihuahua will not eat Heartguard even chopped to teeny pieces & mixed with chicken! I guess she smells it.So the only way to get her heart worm medicine is with Sentinel. I crush the tablet into granuales & add it to her dinner.For some reason my vet doesn't stock it any longer so I have to now buy it online, no problem, arrived within a week. by on 03/22/2014
  • Sentinel Heartworm Preventtive
    I have been using this heartworm preventative for a long time. I have never had a dog with heartworms and felt okay with not testing regularly - it didn't seem necessary- my dogs always are in peak condition. by on 03/14/2014
  • My dogs like it !
    Gives great protection from fleas....ticks.....heartworms...and several other pests. Dogs like the taste and you can give it as a treat or put it in their food . It is a little pricey....but less than some of the combined meds. Buying them separate is more expensive. by on 03/05/2014
  • Highly recommend for all dog owners!
    I have two dogs who play at public parks, the levee and swim in the Mississippi river. Sentinel is excellent for preventing heart worm and controlling or eliminating any problems with fleas. I couldn't be happier with this product. by on 02/21/2014
  • Vet recommended Med
    Easy to use and my dog takes it readily. You only give it once a month. This is what my vet wants us to use. by on 01/21/2014
  • just as expected
    This product is simple and gets job done. I am glad that it came back. Thank you by on 01/02/2014
  • Hands down best product.
    I have used sentinel for years and now using pet care rx I have the convenience of home delivery at a great price. by on 12/29/2013
  • Sentinel
    At first - the dog that I am babysitting spit out the tablet, then I placed it more deeply into a piece of chicken, and viola'. The scratching and biting stopped the next afternoon.Thank you Sentinel. by on 12/26/2013
  • great price and better dosing for very small dogs
    Great price on a highly recommended dog heartworm med. by on 12/22/2013
  • sentinel flavor tabs
    I feel this is one the best all in one flea and heartworm medications out on the market. by on 12/12/2013
  • Not Worth It
    I bought this product because it stated that it is for the, "prevention and control of flea populations, the prevention of heartworm disease and the treatment and control of roundworms, hookworms, and whipworms in dogs." Turns out it didn't do a thing for fleas!!! My black lab is allergic to fleas and this product did nothing for her. When I took her to my vet, they told me that Sentinel doesn't actually prevent fleas, as the product review would have you to believe. So I now have 5 months worth of an expensive heartworm treatment, seeing as how I'm going to have to purchase an additional treatment for fleas. Will never buy this again and Molly will be back on Trifexis as soon as a months time is up!!! by on 12/10/2013
  • great features
    I just started using it and for right now it seems to be as good as what I got from my vet before. by on 12/05/2013
  • Pleased!
    I was pleased by the quick, attentive service of PetCareRx. I haven't had time yet to evaluate the product but based on previous orders with my vet the product is also good. by on 12/02/2013
  • one pill a month for heart worm and flea population
    I would recommend Sentinal highly for your dog especially because of the price from PetCareRx. by on 10/29/2013
  • Sentinel is very effective in preventing heartworm and fleas
    We have given Sentinel to our cocker spaniels since they were puppies. They have never had any problems taking it and it's very convenient to order online. by on 10/28/2013
  • Very happy
    My Freddy love it. I love that he only have to take one pill a month. by on 10/22/2013
  • works great for my two dogs
    My vet does not handle Sentinel and since it has worked so well in the past, I got a prescription for my two dogs andthe order was received within five days. by on 10/19/2013
  • Must taste good
    My dog ate this without any problem. He didn't like his previous heartworm med. I've only given it to him once, and it did seem to upset his stomach, even though it was given with a meal. by on 10/17/2013
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