Treating Heartworm Disease – Another Immiticide Shortage

Once again, Merial has announced a melarsomine shortage of unknown duration. Melarsomine is the active ingredient in Immiticide, the only medicine FDA approved to treat canine heartworm disease.

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. Oh, please do not try to prevent OR treat heartworm disease with “natural” treatments such as black walnut! I love holistic medicine, and keeping pet’s healthy proactively, instead of treating disease reactively whenever possible, but the way to be proactive with heartworm disease is to prevent it with approved veterinary prophylaxis.

  2. 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

    1. 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!

  3. This is so upsetting to rescuers and shelters alike. In the past, in a lot of cases involving HW positive dogs in shelters, rescue groups were their only hope. Due to the cost of treatment to the average pet owner. Now it’s not a matter of cost, it’s that we won’t even be able to have a dog treated. In a foster situation (with only five volunteers active in our state); it will mean really difficult decisions will be made and not saving dogs even when they could be treated and live a long life. We can’t justify a dog sitting on the foster shelves for MONTHS awaiting treatment while other healthy dogs go unsaved.

    Rescue was already heartbreaking making life or death decisions every day – who stays in the shelter, who goes to foster care. Now it’s been made even more difficult.

  4. 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.

  5. 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.

  6. 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!!!!!!

  7. Matt,

    I am so sorry you are going through this with your dog! I have not had any heartworm positive patients during this time when the adulticide is unavailable, but heard that our local shelter, Nebraska Humane Society has one dog who is waiting. So sad!

    From what I understand, vets can call Merial and the company decides who gets limited doses of Immiticide. So have your vet call if he or she has not already. And then make sure your vet has a link to the protocol published by the American Heartworm Societyfor dogs who are waiting for treatment:

    And for now, make sure your dog rests. Which is basically waiting. Which really sucks. I am sorry you are going through this! I hope your dog gets the treatment soon! Let us know.

    1. 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.

  8. Oh man! How frustrating Johanna! I would ask your vet three things-

    1 Since he is classified as Stage One, can he exercise? They may still say “no” because even in “mild” cases, adult worms are present, and the risk is parts of worms could break off and cause emboli, which can be serious and even fatal.

    2 How soon can he be retested? His body’s immune system is trying to clear the infection, but we always prefer to “help” it with treatment (when it is available! :() because it is faster and safer to get rid of the heartworms when they have done as little damage as possible. But maybe he can clear the infection before he is able to be treated.

    3 Ask your vet if they have indeed called, and if not, would they. They will tell you straight out I am sure, and would not mind calling if they haven’t already.

    And finally, this is one of those sad cases where you did everything right and your poor Dog still was infected. The dose of preventative is correct-it is enough for your dog’s size, but safe for a dog half his size (wide margin of safety and good efficacy). I am so sorry! Heartworm disease is awful no matter what, but that is so unfair.

  9. 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.

    1. 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.

  10. Thanks for the input Shawn!!! I called over 30 vets in the central illinois area and found a vet that had the merial–they said they had two left—yeah!!! Kasper will get his shots soon!! Thanks for the help!!!! If you cant find the treatment in a bigger city try calling around to smaller towns who might still have it sitting around due to a smaller dog population;)

  11. It seems a little absurd that this is still going on! We adopted Dash from a shelter who claimed he was heart worm negative and that he had been on preventative. When we took him to the vet, he turned up positive. While he’s not showing any symptoms, even a skin scrape that got a bit of blood in it was completely infested with worms. For now he’s on the Heartguard and has been waiting since August to get treatment. We weren’t just going to bring him back when he turned up positive. Wasn’t his fault after all.

  12. I agree Megan! I do not know why Immiticide is not back on the market yet. So sorry to hear about Dash! Glad you are keeping him of course, but sorry you have to go through this!

  13. I We adopted our dog from LA , He has hearth worm tested neg. My Vet can not get Meds, What can i do ,Iam very worried about my dog What to do ??? STEVEN FROM NEW JERSEY.

  14. Hi Steven. There is no shortage of heartworm preventative medication, so your veterinarian should be able to get that for you. If he or she does not carry products, they can order them for you.

  15. Hi Shawn, I was wondering what your thoughts are on positive heart worm test 6 months after Immiticide treatment. My dog had all 3 Immiticide injections after a (high) positive test. Now, 6 months later, he tests (low) positive. He has been on Heartguard the entire time without fail. What should I do?

  16. On 4/23 I took my dachshund Brandi to her vet with rapid and shallow panting and depression. Heartworm test was neg. , xrays showed left lobe consolidation and some white blood cells were high. Tests for histoplasmosis and blastomycosis were neg. She showed no improvement on several rounds of different antibiotics so we decided to take her to a vet college about a hundred miles away for diagnostic bronchoscopy. There, out of four hw tests only the antigen test showed slightly positive and an ultrasound showed heartworms. So a negative heartworm test doesn’t always mean you are safe. That was two months ago. After being treated with prednisone, doxyclycline and Interceptor she goes tomorrow for her first injection of melarsomine then two more in a month. Her vet had put her some up with her name on it to be sure of having it when it became time to start it. The last week she has been breathing heavier so that scares me about how the medicine will affect her. This is a scary illness!

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