Kudos to KVUE for investigation into confusion over Trifexis

"He lost complete function of his back end. He couldn't walk. He could get up. It was very hard," said Melissa Baker. "He just held his head up almost as if saying, 'Momma help me.' I still have that vision in my head."

From: Terri Gruca, KVUE

Linda Holmbeck's companion of 5-and-a-half years, Toby, started acting strangely last summer while taking a walk.

"It was horrible," said Holmbeck. "He came around the corner, he was ahead of me and he just passed out. I gave him the heartworm preventative Trifexis and he became deadly ill overnight."

Both Baker and Holmbeck had to euthanize their pets and both blame Trifexis.

Holmbeck filed a report with the FDA and Elanco detailing why she believes Trifexis is at fault.

Trifexis has become popular with pet owners because it's the first treatment to combine both a heartworm prevention and something that can kill fleas into one pill.

Since 2011, approximately 70 million doses of Trifexis have been sold in the U.S.

FDA records obtained by the Defenders show thousands of pet owners and vets report dogs became violently ill from the two drugs that make up Trifexis.

That includes more than 23,360 reports about vomiting, more than 1,363 reports of seizures and 344 deaths.

In response to our questions about the drug, Elanco - the company that makes Trifexis - wrote:

"There is no certainty that the drug caused the adverse event". These reports "may have been related to an underlying disease, other drug or other non-drug related causes…"

"We continue to monitor and investigate all the adverse event data and look for potential product-related trends", but "there continues to be no established link between Trifexis use and death."

The FDA is scrutinizing complaints like it does any other drug during the first three years on the market.

"We're very concerned. We're watching things very closely," said Bill Campbell, DVM, a veterinarian at Parmer Lane Vet Hospital.

Dr. Campbell knows Trifexis well. His clinic has dispensed 15,000 doses since 2011.

"People need to be aware. They need to know what to look for," he said. "If you're seeing vomiting, it's time to move to another drug."

Part of the problem in connecting any drug to a pet death is that few people get necropsies on their pets, Baker and Holmbeck among them.

"I started comparing and every time I would give him that pill, within two to three days I was calling the vet. I was at the vet," said Holmbeck. "To me it's crystal clear."

Elanco doesn't agree it is at fault. Arguing, "Neither the attending veterinarian, nor a specialist at Texas A&M believes Trifexis was a factor" in her dog Toby's death.

"You don't want to minimize their grief and distress, but on the other hand we want to be smart about this," said Dr. Campbell.

Both Baker and Holmbeck just want other pet owners to be aware of the potential side effects.

"People need to be aware," said Baker. "They need to know what to look for. If I would have known, if someone had told me when I bought that medicine watch out for these things, if this happens then I would have stopped the medicine immediately, but I never knew."

Their hope is that no one has to see their pet suffer, the way they said Toby and Rhett did.

Elanco does list potential side effects on the label, among them vomiting, diarrhea and seizures. Any pet owner who has concerns can contact Elanco at 888-545-5973. You can also file a report with the FDA here.

How to look up your pet's medicines

The complaints pet owners file with the FDA are online. It's important to keep in mind that these reports do not necessarily link a pet's death with a drug, they are what pet owners believe is to blame for their pet's condition. You can type in any pet drug name and find the reports pet owners and vets have filed here.

More information on the Adverse Event Reports from the FDA

1. For any given ADE (Adverse Drug Event) report, there is no certainty that the reported drug caused the adverse event. The adverse event may have been related to an underlying disease, using other drugs at the same time, or other non-drug related causes. And, this listing does not include information about underlying diseases, other drugs used at the same time, other non-drug related causes, or the final outcome of the reaction.
2. The accuracy of information regarding the ADE is dependent on the quality of information received from the veterinarian or animal owner.
3. Accumulated ADE reports should not be used to calculate incidence rates or estimates of drug risk, because there is no accurate way to determine how many animals were given the drug. For example, if a drug is widely used to treat certain conditions, there may be more ADEs for that drug than another product that is not used as often. This would not mean that the first drug was more unsafe than the second. The number of reports simply represents the numbers of ADEs received for a particular drug, by species, and route of administration.
4. Information on how the drugs were used (for indications on the product label or in an extra label manner) is not provided.
5. Adverse experiences are listed by the active ingredient of each drug in the ADE Report. One of the active ingredients in the list may represent more than one brand name. Interested individuals can find a complete list of brand names associated with each active ingredient by using Animal Drugs @ FDA and selecting Section 2:Active Ingredients.

This is the report the FDA sent the Defenders in regards to the complaints on the two medicines that make up Trifexis – spinosad and milbemycin oxime. These reports are more detailed than what you find on line. Dog issues start on page 7.