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Trifexis® (spinosad + milbemycin oxime) for Dogs

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Trifexis® (spinosad + milbemycin oxime) for Dogs:

Frequently Asked Questions

Q: What is Trifexis?

Trifexis is a monthly chewable tablet for dogs. Trifexis kills fleas and prevents flea infestations, treats and controls hookworms, whipworms and roundworms, and prevents heartworm disease. Trifexis is for use in dogs and puppies 8 weeks of age or older and 5 pounds of body weight or greater.

Q: Should I give Trifexis each month all year round?


The doctors at Argyle Veterinary Hospital recommend giving Trifexis each month all year round.  Due to the warm climate of North Texas, mosquitoes are present throughout the entire year.


Q: Will Trifexis kill heartworms?

Trifexis prevents heartworm disease by killing certain stages that develop after an infected mosquito bites a dog. As with other heartworm preventives, Trifexis does not kill adult heartworms. Speak to your veterinarian about treatment options if your dog is diagnosed with an adult heartworm infection.

Q: Will my dog still need to be tested for heartworm infection while taking Trifexis?


We recommend annual blood testing for heartworm disease even if your pet is up-to-date on monthly prevention, for a few reasons.  In the case of missed or late dosages, protection against heartworm disease decreases.  Most importantly, in the unlikely event that an animal on prevention contracts heartworm disease, your veterinarian needs to know as soon as possible.  Early detection and treatment are very important in terms of your pets well being and prevention of any permanent changes in the heart or lungs.

Q: How should I give Trifexis to my dog?

Give Trifexis with food for maximum effectiveness. Trifexis is a chewable tablet and may be offered as a treat. To help you remember the monthly dosing schedule, stick-on labels are included for your calendar.

Q: How quickly will Trifexis kill fleas?

In a laboratory study of spinosad alone, an active ingredient of Trifexis, spinosad started to kill fleas within 30 minutes and killed 100% of the fleas within 4 hours. Trifexis kills fleas before they can lay eggs.

Q: Does seeing fleas on my dog mean that the treatment is not working?

Trifexis kills fleas before they can lay eggs when used monthly according to the label directions. Remember that all animals in the household should be treated with an approved flea product to help control the flea population. Your dog can continue to be exposed to the fleas that live in the environment. When fleas jump onto your dog, they will be killed by Trifexis. If within a month after your dog receives Trifexis you see fleas on your dog, it is most likely that these are new fleas. These new fleas will be killed before they can produce eggs that contaminate the environment. Continued monthly use of Trifexis can prevent any new infestations.

Q: What if I see worms in my dog’s stool during the month after administration of Trifexis?

Trifexis is indicated to treat and control intestinal parasite infections of adult hookworms, roundworms and whipworms. In occasional cases, it is possible that the action of Trifexis in killing the intestinal worms will lead to the dog expelling them in the stool.

Q: Can other medications be given while my dog is taking Trifexis?

Yes, Trifexis has been given safely with a wide variety of products and medications. Your veterinarian should be made aware of all products that you administered and/or intend to administer to your dog.

Q: Can Trifexis be given to cats?

No. Trifexis is not registered for use on cats. Trifexis was developed exclusively for administration to dogs.


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