Fortunately, there IS a treatment for heartworm infection (stages I-III)
While heartworm treatment is highly effective and most treated dogs do survive, the treatment is not something to take lightly. It is painful and dangerous for the dog, rough on the caretakers, and usually very expensive.
Standard treatment consists of giving two injections of an arsenic-based product (Immiticide) 24 hours apart. The injections are given in a painful location -- the muscle close to the dog's spine in the lower back. The adult worms start to die immediately. As their bodies begin to decompose, pieces are "shed" into the dog's bloodstream and filtered out through the dog's lungs. This can cause the dog to cough and gag, or lead (like a blood clot) to a fatal pulmonary embolism.
The dog must be kept confined for a 4-6 week period following the injections to keep his physical exertion to an absolute minimum in order to prevent a rapid heart rate and/or increased blood pressure from forcing pieces of the dead worms into the tiny blood vessels in his lungs and clogging them up.
This generally means that the dog must be kept crated or penned and allowed out to potty only on a leash. Aspirin may be prescribed to lower the risk of blood clots, though this is controversial.
A safer protocol, sometimes called a "split-dose," "staged-kill," or "three-dose" protocol, consists of giving one injection, waiting one month, then giving two more injections 24 hours apart.
This has the benefit of reducing the worm burden by about 30 to 50 percent with the initial treatment, before the balance are killed by the second set of injections. This protocol is more expensive (since it requires three injections of the drug instead of two) and the dog must be kept strictly confined for a longer period of time. Nevertheless, this split-dose protocol over two months is recommended for dogs with heavy worm burdens (Stage III) or other health problems.
For either short or long protocol, the dog is given a dose of oral Ivermectin four weeks after the last injection. This kills off the microfilaria.
Heartworm treatment recovery is often rough.
Heartworm treatment often causes pain to spread throughout the dog's lower back muscles and makes the dog feel nauseated. Both symptoms will usually ease in a couple of days. As the worms begin dying off, it is common for a dog to cough or gag. Symptom are generally at their peak at 7-15 days after the injections, and this is when the dog is in most critical danger of pulmonary embolism from the dead and decomposing worms. If the coughing/gagging is very heavy, seems uncontrollable, or causes the dog distress, or if the dog has vomiting or any bloody discharge combined with lethargy, fever and/or pale gums, this should be considered an emergency, and the dog should be taken to the veterinary or emergency clinic immediately. Corticosteroids, fluids, and oxygen may be needed at this time to help the dog survive.
Overview of Heartworm Disease
How Heartworm Infection is Prevented
How Heartworm Infection is Diagnosed
For More Information
about heartworms, go to the American Heartworm Society website
or the Pet Center