Heartworm disease is a devastating disease of dogs, responsible for tens of thousands of deaths each year. Most of these occur due to the destruction that these worms do to not just the heart, but the lungs, liver, and kidneys as well. In some cases, the worm burden within the heart and blood vessels can become so great that circulation of blood is actually compromised, resulting in sudden death. Other infected dogs can go years without showing any signs of heartworm disease, seemingly forming a symbiotic relationship with the parasites.

Regardless of its presentation, the presence of heartworm disease puts a tremendous burden on the body's organs and immune system. If your dog is diagnosed with heartworms, there are two treatment options available to you: 1) Fast Kill Treatment; and 2) Slow Kill Treatment. Let's take a quick look at both methods.

FAST KILL TREATMENT

The fast kill, or standard treatment for heartworms employs the use of melarsomine, a compound that is lethal to most heartworms when injected directly into the dog. In most cases, it will eliminate all adult heartworms within four to six weeks.

Prior to treating a dog for heartworms, a complete laboratory work-up, including radiographic Xrays and/or ultrasound, should be performed to determine the status of the internal organs, especially the heart, lungs, liver, and kidneys. If potential problems do exist, a "priming" dose of medication may be administered to allow the body to adjust to the drug. Then in a month or so, if all looks well, the standard treatment is attempted. Ironically, because of the effectiveness of melarsomine, complications can arise, prompting immediate cessation of the treatment series.

Remember: When they die, those worms aren't simply passed from the body like intestinal worms are. Dead heartworms must be processed and dissolved by the dog's body just like any other type of internal "infection". Complications can include loss of appetite, vomiting, and/or the development of icterus, indicating liver inflammation. As the adult worms die, pieces of them might lodge within the blood vessels of the lungs, and if the number of dead worms is extensive, clots can form in the lung vessels, causing severe coughing and lung hemorrhage.

If all goes well with the treatment series, patients are usually discharged from the hospital two to three days after the treatments are started to begin convalescence at home for the next four to six weeks. Heartworm preventative will be given either during or after this time to kill any microfilaria (baby heartworms) still circulating in the blood. Exercise and activity MUST be restricted during this convalescent period, since the heartworms are continuing to die and clots could form if a dog gets its pulse or blood pressure up too high.

Advantages of the Fast Kill Method:

1. Quick kill, reducing ongoing organ damage caused by the presence of heartworms.

2. Prevents new worm infestations (when employed with preventative).

3. Can exhibit up to 100% killing efficacy against all ages of heartworms.

4. Dogs can generally resume normal activities within 45 days of treatment without fear of sudden clots forming in the lungs.

Disadvantages of the Fast Kill Treatment:

1. Expensive ($500 to $1500)

2. Multiple clots in the lungs could form as a result of the massive worm die-out following the injections, sometimes with fatal consequences.

3. Convalescent period is critical; dogs often must be kept in strict confinement to limit activity.

4. Some dogs may have a reaction to the melarsomine itself, with severe reaction resulting in organ damage.

5. Injections are painful.

SLOW KILL TREATMENT

Heartgard Plus (ivermectin) or a similar generic product is given monthly at the normal preventive dose will eventually kill most heartworms, although it can take up to 30 months for this "slow kill" approach to work. Although this method of heartworm treatment is frowned upon by many veterinarians, others feel it still remains a viable options in those instances where finances are a concern or where the fast kill treatment is deemed too risky for the pet (including dogs with extra large worm burdens, dogs under 20 pounds, and dogs exhibiting clinical signs at the time of diagnosis). I concur with the latter group.

Advantages of the Slow Kill Method:

1. Inexpensive.

2. Prevents new worm infestations.

3. Weakens existing worms in the heart and lung vessels, improving the efficacy of the fast kill treatment if that mode of treatment is desired later on.

4. Avoids the safety concerns associated with the fast kill treatment.

5. Can exhibit up to 100% killing efficacy against immature and young heartworms.

Disadvantages of the Slow Kill Method:

1. Blood clot in the lungs could occur suddenly at any time during the prolonged treatment period, especially during exercise or rigorous activity.

2. As long as living worms are present inside the heart and vessels, ongoing damage to the heart, lungs, and other organs can occur.

3. May not work well against older heartworms, especially older female heartworms.

Regardless of which approach you ultimately select for your dog, either one is better than doing nothing at all. And once your furry friend is finally free of these threatening parasites, be sure to keep him/her on the preventive medication each and every month. Its cheap protection and so worth it!

So is your pet.