A veterinarian inspecting a dog with fleas and ticks.

Part of owning a dog involves protecting them from things we can’t always see right away, such as fleas and heartworms. Sentinel is one medication used to prevent such bugs from harming dogs, and it only has to be administered to your pet once each month. But, what are all the benefits and risks associated with this medication?

What is Sentinel?

Sentinel is an FDA-approved veterinary medication used to prevent the following in dogs, according to 1-800-PetMeds:

  • Heartworms
  • Hookworms
  • Flea eggs
  • Roundworms

Sentinel comes in flavored tablets so your dog can enjoy taking medicine.

Is Sentinel safe for dogs?

In some cases, Sentinel can be safe for dogs. Always ask your veterinarian before starting Sentinel treatment with your dog. Sentinel is for dogs who are at least four weeks old and who weigh at least two pounds. Additionally, there may be some instances where Sentinel is not safe for dogs, depending on their breed, any present health conditions they have and if they take any medication(s).


Dosage will be different for every dog, mainly based on the dog’s weight. Sentinel is given to dogs once per month, as directed by the dog’s veterinarian. For specific dosing guidelines, talk to your dog’s veterinarian.

Side Effects

Sentinel can cause your dog to have side effects, including but not limited to:

  • Allergic reaction
  • Vomiting
  • Mood changes
  • Seizures
  • Diarrhea
  • Rash and/or hives
  • Itching

Please note this list is not exhaustive. If your dog experiences ANY of these side effects or any side effects not mentioned above, contact their veterinarian immediately. Some side effects are serious and can lead to major health problems for your dog.

Final Thoughts

Preventative care is an important part of your dog’s health journey, especially when it comes to protecting them from heartworms, fleas and other bugs that could damage their bodies. If you are thinking of starting your dog on treatment with Sentinel, talk to their veterinarian to weigh the benefits and risks first to ensure your pet receives the best care possible.

Disclaimer: This article does not constitute professional medical advice, nor can it replace the advice of a licensed professional.

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