Dog Owners, Vets Deal with Heartworm Medication Shortage

Adult canine heartworm or Dirofilaria immitis can be lethal. The worms inevitably cause pulmonary embolism if left untreated. Unfortunately, the only drug in the United States approved for killing adult heartworms, Immiticde (melarsomine dihydrochloride) is in critically short supply. Merial, the only American manufacturer, began importing limited quantities of Immiticde from Europe on September 30.

Merial will not be able to supply all requests for Immiticide. Merial is urging all vets to conserve Immiticide for the worst cases only. Instead of Immiticide, infected dogs will need to be treated with doxycyline on a rotation of one month on and two months off. So far, there is no shortage of doxycycline. Doxycycline is not FDA approved to kill adult heartworms. If possible, surgery is a last resort to remove living adult heartworms.

What's Going On?

Merial has been limiting its distribution of Immiticide since the winter of 2009. This year, they finally released a statement that they were "experiencing technical issues in their plant that will temporarily affect their ability to provide finished product to us." The main problem was in making the active ingredient. Merial cleared their stockroom on August 9, 2011.

Merial became stingy with distributing Immiticde since then, notes veterinarian Angela Ivy, director of veterinary services for the Richmond SPCA. Shelters across the United States were being denied access to Immiticide. Merial now only sends medication directly to veterinarians. Unnecessary dog deaths from heartworms seem to be inevitable, especially for dogs in shelters.

Heartworm Prevention

The good news is that canine heartworm is preventable. Check with your veterinarian for the oral heartworm prevention medication best for your dog. Most of these medications are made in a tasty liver-flavored tablet that the dog chomps down like any other treat. This medication kills off the heartworm's larval stage, called microfilarae, that lives in the dog's bloodstream. Very rarely, a dog may get shock from the sudden die-off of microfilarae. Always give the medication when you can be around to monitor the dog for the next 8 hours.

Heartworm preventative medications do NOT kill adult heartworms. It's much easier and cheaper to invest in preventative medication for your dog rather than have to go through the expensive and often heart-breaking heartworm treatment.

References

"Merial Runs Out of Immiticide for Heartworm Treatment." Mary Strauss. The Whole Dog Journal. October 2011.

Veterinary Practice News. "Merial to Import Limited Quantities of Immiticide from Europe." September 30, 2011. http://www.veterinarypracticenews.com/vet-breaking-news/2011/09/30/merial-to-import-limited-quantities-of-immiticide-from-europe.aspx

Georgia Veterinary Medical Association. "Immiticide Shortage Update." http://www.gvma.net/i4a/headlines/headlinedetails.cfm?id=125

Richmond SPCA. "Continued Immiticide shortage puts heartworm-positive pets in danger." Dr. Angela Ivy August 16, 2011. http://richmondspca.typepad.com/richmond-spca-blog/2011/08/continued-drug-shortage-puts-heartworm-positive-pets-in-danger-nationwide.html