PFIZER ANIMAL HEALTH: Are Canadian Dogs Different?

REVOLUTION® by Pfizer Animal Health
On Saturday I posted to Facebook about my lovely day, how my dog had a violently epic seizure, and how she attacked me and I received a variety of rather unpleasant and painful dog bites while trying to help her. I wrote about how my wife and I had theorized that she was having negative reactions to her REVOLUTION® heartworm prevention meds.

The first few times she received her monthly treatments, she experienced some pretty serious episodes of vomiting. We didn’t think much of it at first, and it took some repetition before we became suspicious of a link between her vomiting and the medication.

We made the mental note to log and document what happened the next time, that being this month, and the vomiting was replaced with a rather significant seizure just a few hours later.



Warning for REVOLUTION® Selamectin Topical Solution from Pfizer Animal Health in Canada.

I’m one of those people who ALWAYS reads the inserts that come with meds. Not out of paranoia, but for the knowledge of those rare things that could happen. I had read the insert that came with the REVOLUTION® Selamectin Topical Solution before her first round this year, and there was no reason for any concern, nor anything really of note to be aware of.

I re-read the insert last night, just in case I missed anything important.

As you can see, Pfizer Animal Health Canada says there are NO ADVERSE REACTIONS to the REVOLUTION medication in dogs.


Imagine my surprise when I then went to the official corporate site for Pfizer Animal Health – now Zoetis – to review the online information for my dog’s REVOLUTION heartworm prevention medication, and I found a different official insert for the same product, from the same corporation, with a different set of cautionary notes:


Warning for REVOLUTION Selamectin Topical Solution from Pfizer Animal Health in the United States.

PRE-APPROVAL CLINICAL TRIALS: Following treatment with Revolution, transient localized alopecia with or without inflammation at or near the site of application was observed in approximately 1% of 691 treated cats. Other signs observed rarely (<0.5% of 1743 treated cats and dogs) included vomiting, loose stool or diarrhea with or without blood, anorexia, lethargy, salivation, tachypnea, and muscle tremors.

POST-APPROVAL EXPERIENCE: In addition to the aforementioned clinical signs that were reported in pre-approval clinical trials, there have been reports of pruritus, urticaria, erythema, ataxia, fever, and rare reports of death. There have also been rare reports of seizures in dogs.

I’m sorry, but what the heck did I just read?

I do not blame my dog for the bites that she delivered while she was having her seizure and likely in a state of intense fear, panic, and just plain not there. I also accept full responsibility for getting my hands and face too close to a dog in her condition.

It’s the price that I paid for loving my dog and having a temporary lapse of judgment while being more concerned about her state than mine.

Such is life.

A REVOLUTION in Observation and Notification

I can’t scientifically prove that the intense vomiting my dog went through within the first 24-48 odd hours of receiving her initial monthly rounds of the REVOLUTION heartworm prevention was a direct result of REVOLUTION. As I said, at first we didn’t think anything of it, it took some time for us to identify what we thought was a pattern, and why shouldn’t it have when the manufacturer is clearly stating there are NO ADVERSE REACTIONS.

I can’t scientifically prove that our healthy dog who never had a seizure, ended up having a violent seizure within a couple of hours after receiving her final REVOLUTION treatment, and it was a direct reaction to REVOLUTION. Could just be another fluke, right?

However, I think I’m on fairly solid ground to say:

  • My dog is not a fan of intense vomiting, or terrifying and violent seizures. She’s a bit of a wuss.
  • My wife could have done without being temporarily traumatized as our happy and peaceful dog who can’t even kill a damn moth that enters the house because moths are a source of a wonder, briefly turns into Cujo, the Hound from Hell, and attacks me while her eyes are rolling in her damn head.
  • As much of a glutton for punishment that I can be, I’m not overly enthusiastic about being bitten in the face and having my hand chomped on and punctured multiple times. You’ll just have to trust me on this one when I say that it’s … it’s … it’s a little painful and unpleasant.
  • When I go to my vet in Canada and purchase medication from a reputable international manufacturer like Pfizer, with the Canadian division saying there are NO ADVERSE REACTIONS to said drugs, I shouldn’t have to then go to the global headquarters web site of the very same company in a foreign country to find out that there MOST CERTAINLY ARE KNOWN ADVERSE REACTIONS to REVOLUTION for dogs. Reactions such as vomiting, seizures, and other lovely ailments up to and including … death.

Even with the strictest of safety standards, medical science will always involve an element of risk and unfortunate consequences for a certain percentage of patients. I accept this limited risk and the low probabilities of misfortune in my quest to prevent even worse things.

What I don’t accept is being told there’s no reason for concern when the guy across the lake is getting a different story from the same international corporation about the same product.

If the important insert of cautions and warnings that I received from Pfizer Animal Health Canada included the same cautions and warnings given to American dog owners by Pfizer Animal Health HQ, this extended situation would have been avoided – assuming REVOLUTION was the cause – because I would have played it safe and discontinued use after the very first incident.

I take the time to read the provided cautions, and yet I’m still not informed?

This irritates me.

  • Arron Driscoll

    Pfizer, in any form is only a small step about Josef Mengele. They have been fined for human drug trials in Africa, and numerous other ‘misadventures’.
    I am sorry for your pet, but you when Pfizer is involved, face bites may be a best outcome.

  • John

    I agree with Arron. In addition. This happens with any medication that crosses the border. If you’ll notice, Canadian law does not require medications or foods to include exact ingredients or side effects there of. However. The laws down south, all medications and sources of sustenance are required to not only include exact ingredients, but possible side effects. Watch an American TV channel the next time they show any medication commercial. Now watch the same commercial on Canadian TV. I’d suggest informing your vet about this, you probably have already but I say this ‘reminder’ because in a time of concern people can get a bit distracted. Also consult legal counsel about the subject.

  • Zoetis

    Zoetis is dedicated to providing veterinarians and pet owners with quality products, and we monitor their performance and safety in usage. We are sorry to hear that you had a bad experience and would like to investigate the case. Could we please ask you to contact the Product Support team at Zoetis Canada at 1-800-461-0917.

    • I would be happy to take the time to assist you by providing any answers you might need, but as I mentioned in my earlier reply to your post on Facebook, first you need to explain why you are providing different advisories to consumers.

      Zoetis Canada has access to the very same information that Zoetis in the United States shares with its consumers, yet this information is not conveyed to Canadian consumers in the drug inserts. Not only is such important information omitted, the insert goes so far as to say there were NO ADVERSE REACTIONS.

      If Zoetis Canada isn’t sharing important information that comes from its own scientists and medical researchers in another country, I just don’t feel that sitting on the phone with a customer service rep to discuss my personal unscientific theories and observations is a worthwhile use of my time.