Expert: Dr. Louis N. Gotthelf - 5/18/2011

Question
Okay, please don't judge my pet ownership credentials. I have 3 dogs, a mother and two daughters, 5-4-4. All have always been well cared for. One of my dogs I suspect may have heart worm. I recently went thru a bout of unemployment, and simply can not swing the conventional treatment and definitely not the 2 day observation cost. Please way in on whether this is viable. I am considering giving my dog the heart guard monthly maintainer, less effective I know, but will it eventually kill off the worms over time, and since the death rate will be slower, wont that alleviate the main reason for observation, by reducing the risk of a large quantity of worms flowing thru the system all at once. Or at the very least will it have any positive effect, even holding the worms in check or slowly reduce them until I can save the money for the main course?

Any input would help, I know I am gambling with a serious issue, hence why I am here.

Answer
If the dog has heartworms (a simple blood test will tell you) and you give the preventative, no more NEW worms will mature in the dog's heart.  However, since heartworms can live 7 years, the death rate is extremely slow.  The problem with heartworm disease is not the heartworms themselves, but the damage that they do to the lining of the pulmonary artery.  When that artery is narrowed from the worm irritation, less blood flows to the lungs and it will cause exercise intolerance and backup of blood through the right ventricle of the heart.  So you are not doing your dog any favors treating heartworms that way.  If you want to save some money,it has been shown that just one shot of Immiticide, the drug we use to kill adult heartworms, kills off a significant number of the adult heartworms.  We usually do a 2 or 3 shot treatment to increase the kill rate. It is expensive medication.