Editor’s Note: As of December, 2011, Immiticide was again available through Merial’s European source.
Recently, Merial announced that the only FDA-approved heartworm treatment medication,
Immiticide, had become completely unavailable. Previously, we received word from Merial that the medication was in short supply. Unfortunately, efforts to restart manufacture have failed.

What does that mean for you and your dog?

If he is heartworm-free now, it only means that you have more incentive than ever to be sure his heartworm preventive is administered on schedule every 30-31 days. Don’t ever be late.
If your dog has heartworms now, his treatment may be modified, according to two scenarios.
If your pet’s doctor has no Immiticide, he may be able, under strict medical supervision, to begin heartworm preventive for your pet so that he doesn’t get more heartworms. The monitoring and associated steps are very strict. Do not attempt this at home.
If your pet’s doctor has Immiticide in stock, he may modify his usual heartworm-treatment regimen in order to conserve remaining supplies of Immiticide.
Here’s how that works. Immiticide comes packaged as a dry powder in 2-milliliter (ml)vials.

A 2-ml vial of reconstituting liquid accompanies each vial of medicine. One vial treats approximately 44 pounds of dog. If a dog weighs 40 pounds, a little medicine is left over. However, that reconstituted medicine is effective for only 24 hours. If no other dogs are treated within 24 hours, that remaining contents of that vial must be discarded.
However, if two or more dogs are close together in their treatment schedules, putting their appointments on the same day allows veterinarians to utilize Immiticide that would otherwise be wasted.
We have a very small stock of Immiticide that will complete treatment for the diagnosed dogs we already have in queue. Thus, we are scheduling our two Annies, pictured above, on the same day, which will leave us almost no wasted, leftover Immiticide.
So, if your veterinarian requests a change in schedule for your dog’s heartworm treatment, be understanding and know that the maximum number of dogs can be treated with a little cooperation.
See you tomorrow, Dr. Randolph.