Heartworm disease is a very serious and potentially fatal medical condition. Heartworm is a parasitic roundworm that is spread by mosquitos.  Mosquitoes carry the parasite, transferring the infection when they bite. When a mosquito carrying the larvae bites an animal, the larvae are transmitted to the bloodstream and then mature in the heart, multiply by the hundreds, and can grow to 12-14 inches long. Even if your dog is an "inside dog" it is still susceptible to getting heartworms. Many cases of heartworms are treatable, however treatment is very hard on the animal (and requires the animal to be kept quiet in a crate for 4-6 weeks during treatment) The treatment can also make the dog feel very ill for days even weeks after the injection used to kill the heartworms.  Not all cases can be treated, and can still be fatal for the animal.  The treatment is also very costly compared to the cost of keeping your pet on monthly preventative. Keeping your pet on monthly preventative is just as important as their annual vaccinations. The cost of treating heartworms can range from $500-$850 depending on the state you live in.  A monthly preventative is available from your veterinarian or online pet medication stores.  A one year supply of Heartworm prevention for a 150 lb dog can be purchased for under $100.  For more information on heartworms, please visit the American Heartworm Society.

Credit for this graphic goes to Hill's Atlas of Clinical Anatomy,

Published by Veterinary Medicine Publishing Company, Inc.