PetMD Editorial
Written by:
PetMD Editorial
Published: November 7, 2012

Drug Info

  • Common Name: Sentinel®
  • Drug Type: Parasiticide
  • Used For: Treatment of fleas, ticks, heartworms, mites
  • Species: Dogs, Cats
  • Administered: Tablets
  • How Dispensed: Prescription only
  • FDA Approved: Yes

General Description

Milbemycin is used to prevent heartworm and other parasitic infestations on your pet. It is found in two drugs, Sentinel® (Milbemycin Oxime and Lufenuron) and Interceptor (Milbemycin Oxime only).

Sentinel® is to be given every 30 days, preferably on the same day every month to treat and prevent fleas and other parasites. Your veterinarian may prescribe lower doses daily to treat dogs with mange.

Always give Sentinel® after a full meal to ensure adequate absorption.

How It Works

Sentinel® contains Milbemycin Oxime, which is effective against internal parasites such as roundworms, hookworms, whipworms, and young heartworms. It works by interfering with the central nervous system of the heartworm larvae. It is not effective against any stage of the flea life cycle.

Sentinel® also contains another active ingredient, Lufenuron, which prevents egg production in fleas. Lufenuron does this by preventing the flea larva from being able to make chitin, which makes them unable to produce an exoskeleton and grow. Sentinel is not effective against adult fleas, but prevents growth of the infestation on your pet. These adult fleas will still be able to feed on your pet and cause itching and discomfort. Another drug, usually nitenpyram, will have to be used to kill the adult fleas.

Milbemycin is not effective against the adult form of the heartworm, so it important to test your pet for heartworms before administering Sentinel®.

Storage Information

Store at room temperature.

Missed Dose?

Give the dose as soon as possible. If it is almost time for the next dose or you have missed many doses, skip the missed ones and continue with the regular monthly schedule. Do not give your pet two doses at once. Notify your veterinarian that you missed a dose.

Side Effects and Drug Reactions

Sentinel® may result in these side effects:

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

Sentinel® does not appear to react with any other drugs. Sentinel® can be used in dogs starting at 4 weeks of age. It is not safe to use in cats.

Studies have shown that the Collie breed and other herding dog breeds may be more sensitive to elevated levels of Milbemycin and more likely to have adverse reactions including coma and death. If you are concerned, discuss the safety of Milbemycin with your veterinarian. Some forms of Milbemycin are flavored with pork extracts and may cause a food allergy in sensitive pets.

Pets with high levels of heartworms in their system may react to Milbemycin. Have your pet tested for heartworms before administering this drug. Also, please discuss the safety of Milbemycin with your veterinarian when concerning a pregnant or lactating pet.

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