Trifexis For Dogs Heartworm Prevention And Parasite Control

Trifexis for dogs is a monthly heartworm prevention for dogs medicine which also gives protection against intestinal worms and fleas in a monthly tablet which is chewable.

The fact that it also protects against worms and fleas makes it convenient and easy for owners to administer and saves money on buying individual treatments for each problem

Trifexis is for both dogs and puppies provided they are more than five pounds in weight and at least eight weeks of age.

Trifexis for dogs works to:-

  1. Prevent heartworm disease by killing the juvenile heartworm microfilariae
  2. Kill adult fleas
  3. Treat internal parasitic infections with adult hookworm, roundworm and whipworm.

Trifexis for dogsTrifexis for dogs, is a treat as it is beef flavoured and chewable so it is easy to get your dog to take it. It is recommended that you give this medicine with food for it to be most effective. You need to be sure to give the correct dose for the weight of your dog. If your dog is sick within one hour of taking the medicine, the manufacturers advise that you give another complete dose.

If you are ever concerned that your dog has not taken the full quantity of the medicine or that you have missed a dose, contact your vet as protection against heartworm may have been reduced. The makers of Trifexis advise that if you miss a dose, you should give the medicine immediately you realise this and give the next dose in thirty days from then. Also they advise that your vet may want to test your dog for heartworm after six or seven months. Additionally, it is important to contact your vet immediately if you have accidentally given your dog too much of this medicine.

For effective protection against heartworm, the advice of the American Heartworm Society and most vets is that you should give heartworm prevention medicine all year round on the same day each month. The makers of Trifexis advise that protection may be reduced if the interval between doses is greater than thirty days or you do not continue with the medicine for at least three months after the end of the mosquito season.

Trifexis for dogs contains two active ingredients:-

There is not a generic version of Trifexis on the market at this time.

  1. Milbemycin oxime which kills the juvenile larvae of the hearworms that your dog has been exposed to during the preceding thirty days as well as adult hookworms roundworms and whipworms
  2. Spinosad kills adult fleas quickly, preventing them from reproducing and the consequent infestation of fleas as a result.


As with any medication designed for the prevention of heartworm, if your dog has not previously been continuously on a heartworm preventative, you should ask your vet for a heartworm test. It could be dangerous for your dog to take this medicine if he is already infected with adult heartworms.
Hookworms and roundworms can be passed to people – please see our published articles on these two parasites for steps you can take to protect yourself and your family from infection and protect your dog from future infection with these parasites.

Before your dog starts taking Trifexis, you should be sure to discuss with your vet, any other medication or supplements your dog is taking as your vet will be able to advise about any possible adverse interactions that could cause a problem for your dog.

Trifexis is a very safe medicine. However, some dogs may be allergic to the beef in the chewable, some may be hypersensitive to the active ingredients. If your dog has suffered from epilepsy discuss this with your vet before starting your dog on the medicine. At the dose recommended, Trifexis should be safe for use in collies and herding dogs but this is something you should discuss with your vet and even if you are sure your dog has not received more than the recommended dose, if you notice any signs of trembling, weakness or staggering, dilated pupils in the eyes or the odd behaviour of pressing the head against a wall or hard surface within eight hours of taking the medicine, contact your vet immediately.

In addition, you should take veterinary advice if you own a stud dog or breeding bitch before starting them on this medication.

Whilst side effects are rare when taking this medicine as directed, you must contact your vet if your dog exhibits lethargy, vomiting or diarrhea, any itching, swelling or reddening of the skin. Vomiting is more usual in puppies less than four months old who are taking this medicine.

Sometimes, very rarely, an allergic reaction occurs which could result in any of the above symptoms plus seizures, paleness of the gums, a low body temperature, particularly in the limbs, symptoms of shock and, in severe cases, coma. If any of these happen, you must treat it as an emergency and get medical treatment for your dog immediately.

Trifexis for dogs does not need to be refrigerated but it is best stored in a cool dark place, well away from children and pets who may be tempted by a tasty treat. Dispose of any unused medicine carefully.

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