Comfortis the flea-killing wonder-drug, and the general state of flea drug resistance

Patty Khuly, DVM
By Patty Khuly, DVM on Mar. 29, 2008
Comfortis the flea-killing wonder-drug, and the general state of flea drug resistance

Living in Miami as I do, I’ve been seeing serious flea cases over the past few months. Though it’s been cool and we’ve been suffering drought conditions for the third straight year, the fleas seem to be attacking with a renewed vengeance.

Maybe I say that every year. Indeed, I offered you a post not so long ago on the question of flea product resistance.

It’s true that my clients are convinced of the incomplete efficacy of the flea meds relative to their effect of years past. Though my own dogs are seemingly unafflicted by the wily bugs, I have to take my clients’ word for it: the Advantage and Frontline aren’t cutting it.

Over the past year, I’ve taken to recommending their stepped-up use in cases where fleas continue to do their damage. For my flea allergic cases, that means alternating between Frontline and Advantage every two weeks, along with Capstar (an oral, up-to-once-a-day fleabuster) every two to five days.

Yet the drug companies and universities reject claims of resistance. They cite their continued efficacy to similar levels as in years past, sampling fleas from far and wide to ensure the killing power of their drugs. But that hasn’t kept other companies from seeking new, more effective products for our still-affected pets.

In January, Eli Lilly introduced the drug Comfortis (spinosad), a monthly oral treatment for fleas available by prescription only. But would it work?

The drug company’s samples didn’t go far in my hospital. The six pets I treated did so well my clients begged for more. The worst afflicted were my multi-pet households, especially those with Typhoid Mary cats. Fresh from the wilds of their adventures, indoor-outdoor cats are notoriously credited for bringing the fleas indoors and colonizing their buddies with the unwanted insects.

Though I cautioned my clients about the gastrointestinal effects (it reportedly causes mild vomiting for a couple of days in about twelve percent of pets), none complained of any symptoms in their pets. They just wanted MORE!

That’s why I was already disposed favorably towards the drug by the time I made it to the lecture last Thursday night. I wanted to place an order, pronto, knowing my clients would snap it up happily. Though I tried to script it out in the interim, I only found one Internet source carrying it—illegally, I came to find out. (This was and I caution you to stay away from them as, according to my Lilly rep, this product has been diverted and its safety cannot be guaranteed.)

Comfortis will NOT be available online. And so far it’s not available for cats — not yet, anyhow. The company’s working on determining feline safety at present. In the meantime, Revolution seems the most effective in our felines.

I know that seems a tad off from what we know about its efficacy in dogs, but our dematologist lecturer from UC Davis, Dr. Peter Ihrke, assured us this was his top choice for cats due to its different metabolism in kitties than in dogs.

So that’s the skinny for all you flea sufferers. If the other products aren’t doing their thing, consider Comfortis. It’s working out for me so far, though I caution I’ve only used it in six patients. (Though it’s definitely gives ME comfort to know my local dermatologists are happy with it, too.)

Stay tuned, I’ll surely offer you a follow-up post on how Comfortis is shaping up and how Promeris, another new product I’ve yet to use, might rival its efficacy.

Patty Khuly, DVM


Patty Khuly, DVM


Help us make PetMD better

Was this article helpful?

Get Instant Vet Help Via Chat or Video. Connect with a Vet. Chewy Health