It takes weeks after the death of the worms before the body dissolves them out of the circulation and opens all those clogs. They’ll do it, but it’s a slow process, like termites eating your house. You’ve heard that you shouldn’t get an air-bubble injected - how about a handful of foot-long worms? The only way to get rid of them is to let the body’s microscopic white blood cell defenders eat them. With heartworms, they clog up the works like a blood clot would (except that few blood clots are a foot long). With intestinal worms, you kill the worms and they leave the body with the next bowel movement.
Unlike an intestinal worm infection (hookworms, roundworms, tapeworms, etc.), there’s no exit here. Worms who have been swimming upstream, keeping the artery open, float downstream and clog up the works. This is ALWAYS what happens when the dog is treated to kill the heartworms. Indeed this does happen in some dogs, though most infected dogs develop the less dramatic signs of congestive heart failure: weight loss, coughing (especially after exercise), labored breathing, fainting spells and so forth. If he ran hard, increasing heart rate and blood pressure, the damaged artery could blow out, hemorrhaging into the lungs. The dog might get a secondary pneumonia in this damaged area. This would clog the artery either partially or completely, resulting in poor circulation to the downstream area of lung. If they just floated, the pressure in the artery would force them downstream until they hit a branch too small to pass. When there are so many worms present that they clog the outflow from the heart (like roots in a pipe), the heart wears out (prematurely) from the constant overwork of pushing blood through the clog.Īctually the worms don’t just float - they swim upstream. The worms don’t eat the heart or arteries, they just float.
If you open this dog at post-mortem, even though there may not be huge numbers of worms, you can cut the lung way out at the edge and find worms in the blood vessels. Most of the worms will actually be in the pulmonary arteries (taking blood from the right side of the heart to the lungs to get oxygen). In a dog with a lower worm burden, there are not so many worms in the heart. If you do a post-mortem on a dog who has died from heartworms, you’ll find a lot of them there. The conventional view is that the worms are in the right ventricle of the heart, and the big pulmonary artery trunk. Treating the dog who has adult, foot-long worms in his heart - that’s a different story. Prevention of the disease with monthly preventive medicine has been effective most of the time. Treating a dog to clear him of heartworms is a situation where the state of the art is not perfect. Sometimes it results in the patient receiving no effective treatment because he’s busy getting some quack remedy that does nothing at all (or kills him. Sometimes this results in better treatments.
When the standard treatment for a disease fails to satisfy all four of those requirements, people begin to look for alternatives. If it were also easy to do, and inexpensive, that would be perfect. The perfect treatment for a disease needs to satisfy several requirements: the treatment should be 100% effective and it should be completely safe for the patient.