A recent comment on a post about K9 Advantix caught my eye. Patrick wrote, regarding Advantix:

It will kill your cats and dogs if given in too high of an amount, which is easy to do with the amount in a single tube. The same chemical used in it to kill ticks was used in an earlier flea control product and was deemed unsafe by vets. Somehow the Bayer company repackaged essentially the same products but got vets to accept it. This product should NOT be sold over the counter and ONLY vets should apply it in control and monitored circumstances. It’s the human equivalent of using Vioxx, Crestor, or even Lithium. I fear this is an example of corporate profit being put ahead of public health.

I have been ruminating on this matter quite a bit lately. With regard to K9 Advantix, I believe that the many, many layers of lipstick applied to the permethrin pig have, in fact, convinced many veterinarians that permethrin is somehow safe (K9 Advantix consists of Advantage with permethrin added to kill ticks). But in my opinion it is not.

Permethrin and related products were the original ones used to kill fleas and ticks. They are extremely toxic to bugs, quite toxic to cats, and mildly toxic to dogs. In the olden days, they were all we had.

Then came Advantage. It is very effective and supersafe against fleas, but it does nothing against ticks. When Frontline (also very safe and very effective) came along, it was marketed as both a flea and tick product. And that’s where the problems started.

Advantage lost market share, so its manufacturer evidently decided to compete by adding an old-school, not-so-safe product (permethrin) to its originally great product to claim efficacy against ticks. The catch: The product is completely unsafe for cats, and much less safe (in my experience) for dogs.

To add insult to injury, the patent on Frontline expired, so its manufacturer suddenly decided that something stronger was needed for ticks — thus was born Certifect, with an all-caps warning: DO NOT USE ON CATS.

In my opinion, if a flea and tick product isn’t safe for cats, then it isn’t safe. Period. The good news: The safe products (including fipronil, the active ingredient in Frontline) still work. And fipronil is now off-patent, which means that it will be readily and cheaply available. Whether you own a dog or a cat, I recommend against using any product that is labeled as unsafe for cats. I have no intention of applying K9 Advantix or Certifect to my pal Buster.