What is milbemycin oxime + lufenuron?
Milbemycin oxime + lufenuron (brand name Sentinel®) is a heartworm disease preventive that also treats internal parasites (e.g., hookworms, roundworms, and whipworms) and controls fleas in dogs.
Milbemycin oxime + lufenuron is also used off label (extra label) in dogs. Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
How is milbemycin oxime + lufenuron given?
- Milbemycin oxime + lufenuron is given by mouth as a flavored chew tablet.
- It must be given with a meal or immediately after a meal to be absorbed effectively.
This medication should take effect within 2 days for internal parasites and within 24 hours for external parasites. Improvements in clinical signs should follow.
What if I miss giving my pet a dose?
If you miss a dose, give it as soon as you remember, and then wait the recommended time for the next dose. Do not give the pet two doses at once or give extra doses. If you are using this medication as a heartworm preventive and more than 8 weeks have passed since giving the last dose, contact your veterinarian for guidance.
Are there any potential side effects?
Milbemycin oxime + lufenuron may rarely cause the following side effects:
- Mild vomiting
- Diarrhea
Serious adverse reactions may occur. If any of the following signs develop, stop giving milbemycin oxime + lufenuron and contact your veterinarian immediately:
- Depression
- Lack of energy
- Weakness, stumbling, collapse
- Itching or hives
- Dilated (big) pupils
- Excessive drooling
- Seizures
- Coma
Are there any risk factors for this medication?
DO NOT USE milbemycin oxime + lufenuron in
- Dogs that are heartworm positive or have not been recently tested for heartworm
- Puppies younger than 4 weeks of age
- Puppies or dogs weighing less than 2 lb (900 g)
- Dogs that are allergic to any component of the drug combination
Some dog breeds are more sensitive than others to milbemycin (e.g., collies, sheepdogs, and collie or sheepdog-cross breeds). This sensitivity is typically due to a specific genetic mutation (ABCB1, previously known as MDR1) that makes them less able to tolerate high doses of certain medications. Doses used for heartworm prevention in milbemycin oxime + lufenuron are safe to use in these dog breeds.
Are there any drug interactions I should be aware of?
Several medications should be used with caution when given with milbemycin oxime + lufenuron, including:
- Azole antifungals
- Cyclosporine (Atopica®)
- Diltiazem
- Erythromycin
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.
Is any monitoring needed with this medication?
- Your pet should be tested for heartworm before receiving any product containing milbemycin oxime. If your pet has a high load of immature worms and is given milbemycin oxime, a life-threatening reaction can occur.
- For dog breeds with potential milbemycin sensitivity, DNA screening may be done before receiving the medication to determine if your dog has the genetic mutation responsible for adverse reactions to milbemycin oxime.
- Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
- At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.
How do I store milbemycin oxime + lufenuron?
- Store milbemycin oxime + lufenuron at room temperature (59°F to 77°F or 15°C to 25°C).
- Store in a dry place away from heat and direct sunlight.
- Do not store this medicine in the bathroom, near a sink, or in any other damp places. Exposure to heat or moisture may reduce the drug’s effectiveness.
- Keep the container out of reach of children and pets. 
What should I do in case of an emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.
