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.
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.
This medication should take effect within two days for internal parasites and 24 hours for external parasites.
What if I miss giving my pet a scheduled dose?
Give the dose as soon as you remember and start a new monthly dosing schedule. For example, if you forgot to give your pet his/her dose on June 1st and remember on June 18th, give the dose on June 18th, and start a new schedule. The next dose your cat will receive would be on August 18th. 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 eight weeks have passed without giving this medication, contact your veterinarian for guidance.
Are there any potential side effects?
When given as directed, milbemycin oxime + spinosad is well tolerated; however, transient vomiting, diarrhea, decreased appetite, drooling, itching, or trembling may occur. Contact your veterinarian immediately if you observe depression, lack of energy, weakness, stumbling or collapse, seizures, or dilated pupils.
Are there any risk factors for this medication?
Milbemycin oxime + spinosad is safe for use in most dogs. This drug combination should not be used in dogs who are allergic to any component of the product or in dogs that are heartworm positive or have not recently been tested.
Some dog breeds (e.g., collies, sheepdogs, and collie or sheepdog-cross breeds) are more sensitive to milbemycin than others. This is typically due to a specific genetic mutation (MDR1) that makes them less able to tolerate high doses of milbemycin. Doses used for heartworm prevention are safe to use in these breeds of dogs (see the handout “Multidrug Resistance Mutation MDR1” for more information).
Use with caution in pregnant or nursing dogs, in dogs with a seizure disorder, in puppies less than eight weeks of age, or in dogs weighing less than 5 lb (2.27 kg) Your veterinarian will advise you on the safety of milbemycin use in your dog.
Are there any drug interactions I should be aware of?
Some drugs can interact with milbemycin, such as cyclosporine (Atopica®), amiodarone, diltiazem, azole antifungal, and erythromycin. Some drugs interact with spinosad, such as ivermectin (high dose), ketoconazole, loperamide, and cyclosporine. Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.
Is there any monitoring that needs to be done with this medication?
Your pet should be tested for heartworm before receiving any product containing milbemycin. If your pet has a high load of immature worms and is given a product containing milbemycin, a life-threatening reaction can occur.
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.
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.
