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PetDosageChart

Sentinel (Milbemycin oxime / Lufenuron) Dosage for Dogs

Antiparasitic combination (macrocyclic lactone + insect development inhibitor) ⏱ Onset: Continuous prevention (give monthly) ⏳ Duration: 30 days

This dosage information is for educational purposes only. Always consult your veterinarian before giving any medication to your pet. Dosages may vary based on your pet's health conditions, other medications, and individual factors.

Content reviewed by licensed veterinarians. This information is sourced from veterinary drug references including Plumb's Veterinary Drug Handbook and the Merck Veterinary Manual.

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Sentinel Dosage Chart for Dogs by Weight

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Weight Low Dose Standard Dose Max Dose Frequency
5 lbs (2.3 kg) 1mg 1mg 2.5mg Once monthly
10 lbs (4.5 kg) 2.5mg 2.5mg 4.5mg Once monthly
15 lbs (6.8 kg) 3.5mg 3.5mg 7mg Once monthly
20 lbs (9.1 kg) 4.5mg 4.5mg 9mg Once monthly
25 lbs (11.3 kg) 5.5mg 5.5mg 11.5mg Once monthly
30 lbs (13.6 kg) 7mg 7mg 13.5mg Once monthly
40 lbs (18.1 kg) 9mg 9mg 18mg Once monthly
50 lbs (22.7 kg) 11.5mg 11.5mg 22.5mg Once monthly
60 lbs (27.2 kg) 13.5mg 13.5mg 27mg Once monthly
70 lbs (31.7 kg) 16mg 16mg 31.5mg Once monthly
80 lbs (36.3 kg) 18mg 18mg 36.5mg (46mg tablet) Once monthly
90 lbs (40.8 kg) 20.5mg 20.5mg 41mg (46mg tablet) Once monthly
100 lbs (45.4 kg) 22.5mg 22.5mg 45.5mg (46mg tablet) Once monthly
120 lbs (54.4 kg) 27mg 27mg 54.5mg (46mg tablet) Once monthly
150 lbs (68 kg) 34mg 34mg 68mg Once monthly

What is Sentinel (Milbemycin oxime / Lufenuron) used for in dogs?

Heartworm prevention Flea development prevention Intestinal parasite control (roundworms, hookworms, whipworms)

How to give Sentinel to your dog

Give the Sentinel flavored tablet by mouth once monthly with a full meal to ensure maximum absorption. The tablet size is based on your dog's weight — use the size recommended by your vet. Most dogs eat the flavored tablet willingly. If your dog won't take it voluntarily, hide it in a small amount of food or a pill pocket. Mark your calendar for consistent monthly dosing. A heartworm test is required before starting treatment.

Available Forms

Flavored tablet

Give with Food?

Yes — give with food

Side effects of Sentinel in dogs

Common side effects

Vomiting
Diarrhea
Decreased appetite
Lethargy

Serious side effects

  • Allergic reaction
  • Seizures (rare)
  • Hypersalivation
  • Shock-like reaction if dog has existing heartworm infection

When to call the vet

Call your vet immediately if your dog shows any of these signs:

  • Vomiting within an hour of giving the tablet
  • Signs of allergic reaction (facial swelling, hives, difficulty breathing)
  • Severe lethargy or weakness after administration
  • Seizures or tremors
  • You missed more than one monthly dose (heartworm retest may be needed)

Related Medications for Dogs

Macrocyclic lactone (avermectin) antiparasitic

Revolution

Selamectin

For Flea prevention and treatment

View dosage chart
Antiparasitic combination

Simparica Trio

Sarolaner / Moxidectin / Pyrantel

For flea prevention

View dosage chart
Antiparasitic combination

Heartgard Plus

Ivermectin / Pyrantel

For heartworm prevention

View dosage chart
Antiparasitic combination

Trifexis

Spinosad / Milbemycin Oxime

For flea prevention

View dosage chart

Sources & References

The dosage information on this page is compiled from the following veterinary and pharmaceutical references:

  • Plumb's Veterinary Drug Handbook — the standard veterinary pharmacology reference used by veterinarians worldwide.
  • Merck Veterinary Manual — a trusted, peer-reviewed resource for veterinary professionals and pet owners.
  • DailyMed (FDA Drug Labels) — official FDA-approved drug labeling and prescribing information for Milbemycin oxime / Lufenuron.

Frequently Asked Questions

Does Sentinel kill adult fleas?
No, Sentinel does not kill adult fleas. The lufenuron component prevents flea eggs and larvae from developing, breaking the flea life cycle over time. If your dog has an active flea infestation, you will need an additional product that kills adult fleas (such as Capstar or a topical flea treatment) alongside Sentinel.
Why does my dog need a heartworm test before starting Sentinel?
Giving heartworm prevention to a dog already infected with adult heartworms can cause a severe, potentially fatal reaction as the microfilariae (baby heartworms) die off rapidly. A negative heartworm test must be confirmed before starting or restarting any heartworm preventive.
Should Sentinel be given year-round?
Yes, most veterinarians recommend year-round heartworm prevention regardless of climate. Mosquitoes can appear during unexpected warm spells, and the intestinal parasite protection is beneficial year-round. Missing even one month can leave your dog vulnerable.
Can Sentinel be used alongside tick prevention?
Yes, Sentinel does not protect against ticks, so a separate tick preventive (such as a tick collar or isoxazoline product) is often recommended. Discuss combination options with your vet to ensure full parasite coverage.
What if my dog vomits after taking Sentinel?
If your dog vomits within 1-2 hours of taking Sentinel, the full dose may not have been absorbed. Contact your vet — they may recommend giving another dose. Giving Sentinel with a full meal improves absorption and reduces the chance of stomach upset.

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