Heartworm Prevention Medication Shortage in America

I had to take Hugo to the vet today (Valentine’s Day) for his annual vaccinations and check-up. While I was there, I thought I’d pick up a six month’s supply of chewable heartworm prevention medication tablets for both of my dogs. I only received two pills (one for each dog) and was told that no more would come in until March at the very earliest.

The brands Heartguard, Interceptor and Sentinel cleared out its stockroom in January after the manufacturer Novartis shut down America’s only production plant on December 19. Why did they do that? For “voluntary improvements” in response to a scathing FDA report of the plant. In the meantime, Novartis is urging vets to only give out one pill per dog until production resumes in (hopefully) March, but probably not until June.

I Don’t Blame You If You’re Confused

Does this sound familiar? Of course it does. Just this past August, the adult heartworm medication Immiticide ran out to the point where it had to be imported from Europe. Heartworm preventative medication is completely ineffective against adult heartworms. Immiticide is NOT the same as Heartguard, Interceptor and Sentinel. These latter three medications kill juvenile heartworms, called microfilaria. Microfilariae are too small to damage a pet, but can kill a pet once they have matured.

But is the name Novartis familiar to you? If you take the brand name over the counter painkillers Excedrin or Bufferin, then it is. Novartis’ manufacturing plant in Lincoln, Nebraska makes a wide variety of over the counter and prescription drugs for people and pets.

So What Do We Do?

Unlike Immiticide, there are other product alternatives for Heartguard, Interceptor and Sentinel. Talk to your vet to see which medications would be best for your dog or cat. According to The Whole Dog Journal, these products include the brand names Revolution Flea Treatment (active ingredient selamectin) or Advantage Multi (active ingredient moxydectin.) The latter product is for both flea prevention and microfilaria prevention.

But your vet may have a good supply of Heartguard, Interceptor and Sentinel left. These are common medications that veterinary practices normally order in large quantities. Please be patient with your vet and your vet’s office staff as they can only give out one pill per pet per month until the Novartis construction plant opens back up. Also keep up your usual mosquito prevention routine, since microfilariae are passed through mosquito bites.


The Whole Dog Journal. “Novartis Suspends Production of Interceptor and Sentinel.” Mary Strauss. January 9, 2012. http://www.whole-dog-journal.com/blog/Novartis-Canine-Heartworm-Medication-Shortages-20448-1.html

Lincoln Journal Star. “Novartis assumes resuming Lincoln shipments at ‘midyear.’” Matt Olberding. January 25, 2012. http://journalstar.com/business/local/novartis-assumes-resuming-lincoln-shipments-at-midyear/article_a9aeb9b5-8eea-513d-8fe7-12834510594b.html

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