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Trifexis for Dogs – Everything You Should Know

Unfortunately, there is a lot of misinformation about the use of prescription medications like Trifexis for dogs.

The internet is ripe with anecdotal stories of dogs who’ve had serious reactions to drugs like Trifexis but the reality is, if your dog is being treated and monitored by a licensed veterinarian, the medication is much safer than the parasites themselves.

Trifexis is safe to use in dogs 8 weeks or older, and 5 pounds or heavier. Trifexis for dogs provides a triple punch against parasites including fleas, heartworm, and worms like whipworm and roundworm.

Trifexis is considered a broad-spectrum, safe medication.  You should keep in mind that dogs younger than 14 weeks of age tend to vomit after the first dosage.  If that happens within the first hour of administration, you will need to redose your dog.

Don’t Bother with Homeopathic Medicine for Heartworm 

I realize this is a highly controversial subject, but as a regular dog owner like yourself, I really feel that prescription drugs are a sure-thing when it comes to potentially fatal conditions like heartworm.

Alternative or homeopathic dog medicine certainly has its place in dog care, but I believe the most effective way to actually protect your dog from parasites is through prescription, FDA approved medication.  Trifexis for dogs is one of those medications. 

It’s important to always weight the risks and the benefits of any drug you give to your dog. A licensed veterinarian can answer your questions.

Side-Effects of Trifexis for Dogs.

The side effects of Trifexis for dogs include lethargy, mild depression, lack of appetite, and possibly vomiting. 

Some dogs will become itchy or develop mild diarrhea.  Trembling and incoordination are also possible (but rarer) side-effects.  The majority of dogs will have very mild side-effects, if any.  Younger dogs tend to vomit.

There’s a reason that many drugs require a prescription and it’s not because your veterinarian earns a kickback from the company. 

Requiring a prescription means that you have to bring your dog to a veterinarian before you can administer the drug. In doing this, you give your dog the best chance with the least amount of side effects. 

Get the facts on trifexis for dogs.

Before starting Trifexis for dogs, the veterinarian will want to test for any current heartworm infection. In addition, the veterinarian (if your dog has been to this doctor before) will know your dog’s medical history and will be able to make an appropriate decision on parasite control. 

Seizures have been noted in dogs taking Trifexis (although rare), which is why the veterinarian may suggest another drug if your dog has pre existing epilepsy. 

Important Notes You Need to Know about Trifexis for Dogs

Vomiting is not uncommon when dogs take Trifexis for the first time. 

Occasional vomiting is not a serious condition. The most important thing to be aware of is whether your dog vomits within an hour of administration.  If that happens, you will need to redose your dog in order to get complete heartworm protection.

Some dogs taking Trifexis will develop diarrhea. Keep your dog well-hydrated and report back to the veterinarian if the diarrhea gets worse or lasts more than 24 hours.

Precautions in Trifexis for Dogs 

The active ingredients in Trifexis include Spinosad (effectively kills fleas and stops the cycle) and Milbemycin oxime (treats heartworm, adult hookworm, roundworm, and whipworm).

Never give your dog more than the recommended dosage. Trifexis for dogs is considered safe at appropriate dosages.  More of the drug doesn’t work any faster or better. 

Breeding females should not be administered Trifexis. There isn’t much information out there regarding breeding males, so it’s probably best to avoid Trifexis for them as well. 

Trifexis Horror Stories 

The last few years has shown an increase in paranoia and fear over certain prescription drugs.

Trifexis for dogs is taking a hit from the public over safety concerns.  The fact that dogs have died while taking Trifexis doesn’t mean it was the Trifexis that caused the death.  

That’s not to say Trifexis is safe for every dog; however, the history of its use points to safe outcomes time and time again. Parasitic infections like heartworm, however, are always fatal if left untreated. 

Dog owners should be concerned about what they’re giving their dogs, but it’s important to find research that is objective. 

Protecting Your Dog from Parasites 

Trifexis for dogs is used to stop and kill the life cycle of fleas and various worms including heartworm. 
It’s more dangerous to start and stop dosages  based on fears than it is to offer continuous, year-round treatment. Why? Because infestations can’t be cured overnight.

In order for drugs like Trifexis to work properly, it takes many months to effectively halt the life cycle of heartworms.

Read all about the Insane Heartworm Life Cycle in Dogs!

Heartworm may not present any symptoms at all until your dog has been infected for 6 months. 

At that stage, your dog might show symptoms of coughing and the inability to tolerate exercise. This is because heartworms (as the name implies) affect the heart and the heart valves.

As the worms grow and multiply, they will eventually destroy the heart completely. 

How Much and How Often

Unlike natural or alternative treatments, there is no guessing game associated with Trifexis for dogs.

The manufacturers of the drug have conducted studies that point to the safest, most effective dosing requirements. 

Dogs 5 pounds and over can take this drug safely.  Since a prescription is required, you will be in a position to ask many questions about the drug.

You’ll also be given an appropriate dosage based on your dog’s unique needs.

Trifexis for dogs is given as an oral tablet once per month. Your veterinarian will prescribe the dosage appropriate for your dog’s weight.

Do not discontinue use as you will only put your dog at further risk.  Heartworm can recur if the dog is exposed to mosquitoes. The only way to avoid mosquitoes entirely is to keep your dog under lock and key. And nobody is going to do that. 

Other Medications Might Not Work

The truth is, parasites (like bacterial infections) build an immunity to certain drugs.

Drugs of the past may not work as effectively or require increased dosages. Giving too much of a drug is detrimental. Not giving enough won’t provide adequate protection against parasites. 

If you live in an area where there are mosquitoes and fleas, you have to worry about parasitic infestations. Fleas and worms (notably heartworms) can have long-term effects on your dog’s health.  Untreated heartworm is actually fatal. 

The beauty of Trifexis for dogs is its three-in-one protection. It’s easy to administer (one tabet monthly) and can save your dog from many secondary infections caused by parasites like fleas. 

Flea Allergies

Some dogs are actually very allergic to fleas. One bite can cause a dog’s entire body to itch uncontrollably. 

Constant itching and scratching can cause the skin to develop sores and ulcerate. When this happens, bacteria easily penetrates to the bloodstream. 

 Read about the different types of dermatitis in dogs.

Don’t Think Your Area has Heartworms?  Think Again!

Heartworms thrive in humid climates, especially in areas subjected to mosquitoes.

If you’ve ever been camping, enjoy walks or hikes in the outdoors, or live in one of these areas, you know what it’s like to experience that high-pitched whine of a mosquito. He’s nearby but you can’t find him until it’s too late. 

You might suffer an annoying itch. Your dog, however, could be on his way to a heartworm infestation. 

Mosquitoes carry the heartworm larva which is transmitted to dogs when they bite. The parasite burrows through the bloodstream and settles in the heart chambers and arteries. 

Trifexis for dogs is the best way to halt heartworm infestation.

The Dire Consequence of Fleas in Dogs

Fleas are another pest that you don’t want your dog to carry.

They take weeks to kill off (because of the three-week life cycle) and are easily transmitted from pet to pet. The eggs are shed in the dog’s bedding, carpeting, and furniture.

Flea infestations are no fun. Worse, they can cause serious trauma to your dog’s skin. 


Trifexis for dogs is a safe medication designed to protect your beloved dog.

The best way to prevent heartworm, flea, or roundworm infestations is through FDA approved meds. 

In addition, the best way to make sure Trifexis for dogs is as safe as possible is to maintain regular checkups with the veterinarian. 

Having a healthy, active dog requires a little bit of care and prevention. 

Trifexis for dogs should never be given to a dog without seeing a veterinarian first. The reasons, as noted above, are so the doctor can make sure the drug is appropriate and can monitor for side effects before they become serious.

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