Treating Heartworm Disease – Another Immiticide Shortage

Life With Dogs is reader-supported. We may earn a small commission through products purchased using links on this page.

Once again, Merial, a producer of animal health products, has sent a letter to veterinarians announcing a melarsomine shortage of unknown duration.  I received my letter on August 5, 2011.  Melarsomine is the active ingredient in Immiticide, the only FDA approved medication for the treatment of canine heartworm disease.   As with the melarsomine shortage of 2009-2010, any requests for Immiticide must be made directly to Merial by the pet’s veterinarian.

My super cute cousin Sam the Dog is on the melarsomine case!

Heartworm Disease Treatment is Different Than Heartworm Disease  Prevention:

Heartworm Disease Treatment

Immiticide is an injectable medication labelled for the treatment of heartworm disease.  It is produced exclusively by Merial.  Its active ingredient is melarsomine.

Heartworm Disease Prevention

Many different medications are used for the prevention of heartworm disease.  Most are oral or topical monthly medications and one is an injectable product given every six months.  All are available by prescription only.   None are currently scarce or  unavailable.

Should I worry?

If your dog is consistantly on a heartworm preventative medication, he or she is at a very low risk of contracting heartworm disease.  Those hardest hit, unfortunately, will be rescues and shelters, especiallly in heartworm endemic areas, and pet parents who have adopted heartworm-positive dogs, as well as pet parents whose dogs have missed doses of their heartworm preventative medication and become heartworm positive.  Immiticide is still available, but may be difficult to obtain.  The shortage is expected to last “weeks to months.”

The melarsomine shortage of 2009-2010 lasted about five months (December 2009 – April 2010).  A new supplier of melarsomine was found, and in the interim, Merial, the FDA and veterinarians worked together to provide heartworm treatment for dogs who needed it from the existing Immiticide supply and a conditionally approved melarsomine provider.

Will You Ever Stop Obsessing about Heartworm Disease?

No!  PLEASE keep your dogs (and cats and ferrets) on their heartworm preventative medication!  I would much rather have you read this post and move on to the next thing than hear how this issue has broken your heart.

I will also never stop singing the praises of boring.  Heartworm disease medication shortages are exciting.  Routine heartworm prevention is boring.  I love boring.

See full size image

Update!  This was posted by the American Heartworm Society on August 9, 2011:

Guidance for Heartworm Disease Management During the Adulticide Unavailability

23 thoughts on “Treating Heartworm Disease – Another Immiticide Shortage”

  1. you might know this would happen when my tucker turns up positive for heartworms,when on prevention. I had scheduled his treatment and was told today they do not have any immiticide,and don’t know when they will get it. This dog has had the worst luck. ended up in a shelter,adopted out for 3 mos. i adopt him at age 8 mos. and now he has heartworms.Somebody give this dog a break. I have never seen such bad luck given to this sweet dog. Donna

    • Donna:

      Same problem here! I adopted a little sweetie from a family member who lives in Georgia (I live in Illinois). She had gotten the dog from a shelter, and he didn’t receive preventive medicine. I took him into the vet here a couple of days ago for a heartworm test and shot updates, never dreaming he’d test positive, but he did! And no medicine available. The vet did some sort of alternative treatment using Heartgard and other meds yesterday, but that will only kill the larvae. I’m hoping the medicine becomes available very soon!

  2. And, Yes, we do have heartworm in Arizona!! Took my newly adopted shelter dog in for a check-up and heartworm test (because I wanted him put on preventative) and found out he was positive. Wake up AZ!! Get your dogs tested and put and keep them on preventative!! The treatment is long, traumatic for both dog and owner, and expensive. Prevention is easy and inexpensive. You’d immunize your kid from a terrible disease, wouldn’t you? If you make the choice to be a pet owner, show some responsibility to these sentient beings.

  3. Ok. Now that we know the shortage to make IMMITICIDE is with the ingredient Melarsomine, how about we contact Merial and plead that they get some or make some more. Surely, there is a way for a drug company to proceed with this. Media phone number is 1888-301-1539 or go to Merial’s website for e-mail address or other phone numbers.

  4. my dog has heartworms the vet claims that there is nothing they can do in Illionois is this true,,,what should i do? ive been told my vet can call them directly to get it,,,if thats true why wouldnt they have done that instead of having me wait??? help!!!!!!

  5. Hi there, my 10 year old American Pitt was just diagnosed with heartworms. We religiously gave him Heartgard every month, and just so happened to opt in for a $100 blood test during his yearly checkup. The vet called and told us he was positive for heartworms and then told us about the Immiticide crisis.

    The odd thing is, of the three tests, only one showed up positive. Unfortunately, it was the lab test, and the pregnancy-type tests were not positive. One was negative and one was abnormal. We have begun the slow-kill treatment and were told that all of the Immiticide is gone. I am wondering, though, if they just aren’t calling in because he’s still a stage one.

    We are two days into treatment, and this no exercising deal is already really difficult. I am so frustrated, as we have always given him his medicine, so I don’t understand how this could have happened. His weight fluctuates between 97lbs and 101 lbs, and I don’t understand how the same dose for a 50lb dog can be sufficient for a 100lb dog.

    I am going to be calling Merial to verify that they are, indeed, completely out of stock. Your recent post saying that it might still be in supply is encouraging, but I fear we’re looking at a year before we get through this. Any ideas or suggestions you might have would be greatly appreciated.

  6. I’m curious how vets feel about going back to using Caparsolate – even though the risks are higher. Is this even manufactured any longer?

    It seems counterproductive to me that Merial is focusing on the dogs who are physically effected by the disorder and showing serious symptoms. In my experience, the dogs that are symptomatic have a higher tendency of side effects and lower efficacy of treatment success.

    It would seem to me they’d be using the drug for the dogs without advanced disease where it could do the most good and where the tendency of side effects and a higher efficacy would be expected.

    • Hi Rachael! That is an excellent question! I think caparsolate would be an excellent second choice to treat heartworm disease right now, but unfortunately, it is no longer manufactured :/

      I have heard your argument quite a bit too-why not treat the dogs with less severe clinical signs or no clinical signs first since they would have the best prognosis? And I don’t know why but I am guessing that they figure those are the pups who can “hold out” the longest and then when the shortage is resolved, everyone can be treated. Hoping it is soon.


Leave a Comment