WSB-TV: Dog Owners Report Trifexis Related Deaths Every 36 Hours

Trifexis is a popular monthly oral medication for dogs that kills fleas, heartworms, roundworms, whipworms and hookworms.  It also reportedly kills dogs.

When an investigative reporter from WSB-TV in Atlanta requested information on dog owner complaints from the company that makes Trifexis and was repeatedly refused, he filed a FOIA request with the Food and Drug Administration.  The information he received is astonishing:

[The records obtained via FOIA] showed that since Trifexis hit the market, every 36 hours, a pet owner reported that Trifexis killed their dog.


According to FDA records, pet owners have reported 700 dog deaths. That’s 120 more than the deaths linked to Chinese chicken jerky treats. Like the treats, Trifexis is suspected, but not the proven cause.


The FDA numbers also showed 259 of the 700 dogs that died were euthanized.


The new numbers also show a huge jump in the cases of dogs reported sick after taking Trifexis.

The WSB-TV piece points out that while Trifexis is outright hiding the numbers from the media, the FDA website is also woefully behind on updating its numbers.  In other words, consumers who haven’t filed a FOIA request with the FDA themselves and didn’t see the WSB-TV report are most likely unaware of the seriousness of the owner-reported illnesses and deaths linked to Trifexis.

Heartworm medication is important and no one should disavow its use entirely based on this report.  But consumer access to accurate information is also important in order to make informed decisions.  If you are using Trifexis and concerned about the manufacturer hiding the number of owner-reported illnesses and deaths, talk to your vet about one of the many alternative heartworm drugs available.

(Thanks Arlene for the link.)

Novartis Plant Still Shut Down

In January, I posted about the Novartis plant shutdown in Lincoln, NE.  I haven’t seen anything new come across the wire about this and had assumed everything was back to normal.  When I was unable to buy Interceptor (made by Novartis) today due to shortage of product, I began looking around.  The Interceptor website doesn’t have any information.  This Novartis press release, dated February 2, seems to indicate production has resumed at the Lincoln plant – until you read more closely.  It’s a rather deceptive media release basically stating the company has resumed shipping old products they found in the back closet.  Production has not been resumed.  (See the weird disclaimer at the end.)

I eventually called Novartis and a recording told me to visit a website called  From there I was led to this FAQ page which gives information about the shortage and addresses the funky press release from February 2.  The bottom line:  The plant is still shut down and there is no estimated date when it will be operating again.

In re-reading the comments at my original post, reader Charlotte shared a link for where she buys Interceptor (Thank you!).  I went ahead and checked and they do have product so I ordered a package.  Now I’m sitting here with a case of buyer’s remorse, wondering if I should have ordered a product from a company that seems less than forthcoming.  On the other hand, outside of Novartis, I know of no company that makes any product containing just the (non-ivermectin) heartworm and intestinal parasite drugs – which is all I want.

I wonder what is going on at that Novartis plant.

Novartis Temporarily Halts Production on Heartworm Drugs

Here’s one that slipped under my radar last month:

Novartis Animal Health has ceased production of Interceptor, Sentinel and several other drugs manufactured in its plant in Lincoln, Neb., while the facility undergoes “process and compliance improvement activities,” a spokesman for the company confirmed today.

I buy Interceptor for Mulder, my CHD (Compulsive Herding Dog) since she has white feet.  As far as I know, there is no other product on the market that contains only the active ingredient in Interceptor (milbemycin oxime).  I hope the stoppage will be short-lived.


Dude, Suck It

From FL:

A man was jailed on animal cruelty charges after officials reportedly found five sick and underfed pit bulls at his home.
[D]eputies saw two dogs in small wooden cages and others that were infested with fleas and parasites. One pit bull, Poncho, was hacking badly and suffered from heartworm disease.

All of the dogs were taken from Bowens [the owner], who told officials that he knew Poncho was sick but could not get him to a veterinarian because he recently was jailed on other charges.

First off, it takes years for heartworm disease to develop to the point of “hacking badly”. Heartworm preventives are available for little cost, even for a group of dogs, without a prescription, and recommended year round by every Vet I’ve ever known for pets living in the Southeast. I have no idea how long this guy was in jail previously but indeed if it was many years, obviously he should have had someone caring for the dogs.

At any rate, the charges he faces now for the alleged years of neglect of his 5 Pitbulls are only misdemeanors. So he prolly won’t be able to use the “But I was in jaaaaaaail” excuse next time.

If he is found guilty on these cruelty charges, I hope he doesn’t get these dogs back. I also hope the dogs receive the treatment they need and can find permanent homes with owners who will take care of them.


Completely separate cruelty story here, but if these allegations are true, this guy – and anyone who watched this going on and did not report it to authorities – can suck it too.

Heartworm Medications by the Numbers – Dosages for Dogs

Note: I did not go to Vet school and I’m not giving medical advice. For informational purposes, and because I like to research numbers, I’m sharing here some canine heartworm medication dosages along with sources for that information. If you have any questions about the medication you are giving your dog or if you want to make a change to the dosage, please ask your Veterinarian.

Heartworm drugs kill certain stages of heartworm larvae which may have developed in the dog’s bloodstream over the previous 30 days. This is commonly referred to as “heartworm prevention” although that is rather a misnomer. Perhaps it would be more accurately termed “prevention of heartworm larvae developing further”. The two most common heartworm drugs are Ivermectin and Milbemycin Oxime.

The minimum dosage of Ivermectin for heartworm prevention is 6 micrograms (mcg) per kilogram (kg) of body weight, every 30 days. For us non-metric-enians, that’s 2.72 mcg per pound (lb) body weight.

Some brand names of FDA approved Ivermectin tablets which your Vet may sell or you might order online are Heartgard (or Heartgard Plus which adds an intestinal dewormer to the Ivermectin), Tri-Heart Plus (Ivermectin plus intestinal dewormer), (Note: Tri-Heart got into some trouble with the FDA in 2007 over their claim of the product’s effectiveness against whipworms) and Iverhart who offers two products – both containing Ivermectin plus intestinal dewormers.

Rather than manufacture and market dozens of different products for various weights of dogs, pharmaceutical companies typically market just a few products, each one with a range of weights to be treated. For example, a product labeled “for dogs up to 25 pounds” contains the Ivermectin needed for a 25 pound dog. All dogs weighing less than 25 pounds are receiving more than the minimum Ivermectin necessary for heartworm prevention.

In order to dose specifically for the weight of an individual dog, some owners opt to purchase the 1% Ivermectin solution injectable labeled for cattle and dilute it with a suitable liquid (Ivermectin does not mix evenly with all liquids which would throw off the dosing) such as propylene glycol. Or you could purchase the Ivermectin already diluted. The 1% Ivermectin solution contains 10mg (10,000 mcg) per ml. (Note: 1ml=1cc) Diluted to .05% (a 1/20th dilution), each ml contains 500mcg. Looking at Chart A, a 50 pound dog needs a minimum of 136mcg of Ivermectin. Using the diluted solution, that would be about .27 of a cc given orally – not injected. Clearly a tuberculin syringe would be needed to measure this dosage. Alternately, the 1% Ivermectin solution could be diluted further. Note: Many Vets discourage this “off label” use of the cattle version of Ivermectin in dogs as it is not FDA approved. Vets are obligated to advise their clients to use the FDA approved versions of canine heartworm meds on the market – that doesn’t mean it’s unsafe.

The lethal dose for Ivermectin is 10mg/kg in rats. This is a huge dose. Super huge.  In other words, Ivermectin is a very safe drug (unless your dog happens to be sensitive to it).

Edited to add another source for LD50 info on Ivermectin (this dosage differs from the above cited info):

The following information is for the Ivermectin only, not the Horse Health Equine Ivermectin Paste.
LD 50 Mouse, oral 25 mg/kg
LD 50 Rat, oral 50 mg/kg
LD 50 Dog, oral apprx 80 mg/kg

This table has similar values but interestingly shows a difference in LD50 amounts for male and female mice.

And since I’m being an Ivermectin wonk, here’s some more info on toxicity:

Some dog breeds, most notably the collie, exhibit signs of ivermectin related central nervous system toxicity at ivermectin doses exceeding 150 to 200 ug/kg. [Note: ug=mcg]  […] Commonly prescribed veterinary formulations of ivermectin used for heartworm prophyllaxis limit dosages to the range of 6 to 12 ug/kg and are generally considered safe. A severe overdosage of ivermectin is required to produce ivermectin toxicosis.

Back to original post:

Which brings me to my next topic: opting to give your dog more than the minimum required dose. Many people choose to give more than the minimum Ivermectin dose:
– Those who like the convenience of purchasing the medicine in a dose for the top of the weight range but whose dog weighs less
– Those who add the diluted Ivermectin liquid to the dog’s food and don’t want the worry of “What if a minuscule amount got left in the food bowl and my dog got shorted?”

So how much more than the minimum is proven safe to give on a monthly basis? To answer that conservatively, we can look at the bottom weight range in the pre-packaged Ivermectin tablets. For example, if you follow the package instructions for a 51 pound dog, you are giving approximately twice the minimum required Ivermectin each month. Same for a 26 pound dog – the label instructs you to give one tablet monthly and that tablet contains approximately twice the amount needed for the dog’s weight. So the manufacturers and the FDA have approved routine monthly dosing of twice the minimum required amount of Ivermectin for dogs. If you are curious about giving more than twice the minimum dosage monthly, check with your Veterinarian.

The other drug commonly used for heartworm prevention is Milbemycin Oxime and is marketed under the brand name Interceptor as well as others. This drug is administered to dogs at a dose of 0.5 mg/kg body weight (.23 mg/lb) every 30 days. At this dosage, the drug works against heartworm and intestinal parasites. If you are wanting to use the drug for heartworm prevention only, you’ll want to use the “Safeheart dose“. (Safeheart was approved by the FDA in 1998 but never sold in the US.) The FDA states:

This supplement provides for a change in dose for dogs from a minimum of 0.5 mg/kg [which is the Interceptor dose, which also controls intestinal parasites] to a minimum of 0.1 mg/kg with a corresponding restriction in indications to the prevention of heartworm disease only. [bracketed addition=mine]

Interceptor is packaged in the following dosages: 2.3mg tablets, 5.75mg tablets, 11.5mg and 23 mg tablets. Looking at Chart B, the 2.3mg tablet would be the right dosage for a 45 pound dog if you wanted heartworm prevention ONLY. If your dog weighs less than 45 pounds, I don’t know of any options for purchasing smaller doses of Milbemycin Oxime in the US. Splitting pills is one alternative some people use with due care.

Further reading:

Dr. Khuly’s pitch for doing your “civic duty” and giving your dog heartworm meds

Dr. Khuly writes about a few of the reasons owners don’t give heartworm meds when they really should