Those who own or have treated dogs infected with heartworm have been waiting for an update on the 2011/2012 Immiticide shortage. The veterinary profession went into a near panic when drug giant Merial, makers of the only canine heartworm treatment on the market, Immiticide, announced in August of 2011 that they had to temporarily halt distribution of the drug for several weeks to several months. Citing a “technical issue in the plant,” the company went on to say that their inventory of Immiticide was depleted and that veterinarians should work on alternative protocols for treating and managing heartworm disease, such as a combination of steroids, antihistamines and preventative heartworm medication.

At the time, Merial did state that both them and the manufacturer  (Merial outsources the manufacturing) of Immiticide fully understood the implications of the outage of the only heartworm treatment available and said that they were working as quickly as possible to rectify the situation. We have been in communication with Merial Director of Communications, Natasha J. Mahanes, who let us know that, while Immiticide is not yet being mass-distributed as before, it is now being released on a restricted distribution basis. Says Mahanes, “We continue to fulfill customer requests for Immiticide as needed for immediate treatment of a heartworm-positive dog.”

Heartworm, a species of roundworm, infects animals through mosquitoes and it is a disease that is usually fatal if left untreated. Mosquitoes become infected with microfilariae (the young heartworm) when feeding on the host animal. The microfilariae mature to the larval stage over the next 10 to 14 days, and when the mosquito bites another animal, the larvae then enters that animal, infecting him. Within 7 months the larvae mature into adult worms and takes up residence in the lungs and heart. Heartworms are prevalent in all 50 US states, but more so in humid climates where mosquitoes thrive, such as the southern states. While heartworm disease can be devastating, it is simple to prevent with one of several monthly heartworm prevention medications on the market, available through veterinarians.

If you suspect that your dog may have heartworm disease, you can take him for a simple blood test at your veterinarian’s office to find out. There are four stages of heartworm disease, divided into “classes.” Higher classes mean more advanced illness. Class 1 involves no symptoms or an intermittent cough. Class 2 involves mild to more moderate symptoms which include the dog becoming easily tired after activity that didn’t normally tire them before. Class 3 can include poor body condition, fatigue after even mild activity and an increasing, persistent cough. Class 4 is also called “caval syndrome” and can result in such a severe physical blockage of worms that blood flow to the heart is decreased. At this stage of infection, surgery is required and still often results in death.

If your dog has been diagnosed with heartworm disease, the treating veterinarian should call the Merial Customer Care number, 1-888-MERIAL (1-888-637-4251), press option 1 and request Immiticide.