What is milbemycin oxime + spinosad?
Milbemycin oxime + spinosad (Trifexis®) is a heartworm disease preventive and controls internal parasites (e.g., hookworms, roundworms, and whipworms) and fleas in dogs. This medication should take effect within 2 days for internal parasites and 24 hours for external parasites.
How is milbemycin oxime + spinosad given?
- Milbemycin oxime + spinosad is given by mouth as a flavored chewable tablet.
- It can be given with or without food, but if your pet acts sick or vomits after getting this combination on an empty stomach, try giving the next dose with a small amount of food.
What if I miss giving my pet a scheduled dose?
If you miss a dose, give it as soon as you remember, and start a new monthly dosing schedule. For example, if you forgot to give your pet their dose on June 1 and remember on June 18, give the dose on June 18, and start a new schedule. You will give your pet the next dose on August 18. Do not give your pet two doses at once. Contact your veterinarian if you are concerned about a missed dose. If you are using milbemycin oxime + spinosad as a heartworm preventive and more than 8 weeks have passed without giving this medication, contact your veterinarian for guidance.
Are there any potential side effects?
Milbemycin oxime + spinosad may cause the following side effects:
- Transient vomiting
- Diarrhea
- Decreased appetite
- Drooling
- Itching
- Trembling
Serious adverse reactions may occur. If any of the following signs develop, stop giving milbemycin oxime + spinosad and contact your veterinarian immediately:
- Depression
- Lack of energy
- Weakness, stumbling or collapse
- Seizures
- Dilated (big) pupils
Are there any risk factors for this medication?
DO NOT USE milbemycin oxime + spinosad in:
- Dogs that are heartworm positive or have not recently been tested for heartworm
- Dogs who are allergic to any component of the product
USE WITH CAUTION in:
- Pregnant or nursing dogs
- Dogs with a seizure disorder
- Puppies less than 8 weeks of age
- Dogs weighing less than 5 lb (2.27 kg)
Some dog breeds are more sensitive than others to milbemycin oxime + spinosad (e.g., collies, sheepdogs, and collie or sheepdog-cross breeds). This sensitivity is typically due to a specific genetic mutation (ABCB1, also known as MDR1) that makes them less able to tolerate high doses of certain medications. Doses used for heartworm prevention in milbemycin oxime + spinosad are safe to use in these breeds of dogs.
Are there any drug interactions I should be aware of?
Several medications should be used with caution when given with milbemycin oxime + spinosad, including:
- Azole antifungals
- Cyclosporine (Atopica®)
- Diltiazem
- Erythromycin
- Ivermectin (high dose)
- Ketoconazole
- Loperamide
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. A life-threatening reaction can occur If your pet has a high load of immature worms and is given milbemycin oxime.
- For dog breeds with a potential milbemycin oxime 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 + spinosad?
- Store this medication at room temperature in a cool, dry place, away from heat and direct sunlight.
- Do not store this medicine in the bathroom, near the kitchen sink, or in a damp place. Exposure to heat and/or moisture may reduce the medication’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.
