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Heartworm Life Cycle | Climate and Heartworm | Medication
Heartworm disease is a parasitic infection that occurs in dogs (and more rarely in cats) of any age or breed. The heartworm parasite is a worm that makes its home in the affected animal's heart and lungs causing a slowly developing, severe, and frequently fatal illness. Heartworms are transmitted to a pet when the pet is bitten by an infected mosquito. Mosquitos become infected when they bite a dog that already has heartworms. Baby worms, called microfilaria, circulate through the blood vessels of an infected dog and are ingested by the mosquito when it bites.
The microfilaria mature to an ineffective stage within the mosquito. The insect then is able to transmit the infection to dogs when the mosquito bites them. The heartworm larvae stay in the tissues around the mosquito bite for about 2 months. Next they enter the dog's bloodstream, and after three to four more months reach the right side of the heart and the large vessels of the lungs. The worms, which can be up to 14 inches long, reach their final adult stage six to seven months after the original insect bite. Once mature, the adult worms reproduce, creating new microfilaria, thus completing the lifecycle.
Infected dogs frequently do not show symptoms for many months or even years. The symptoms that an affected animal will show are generally those of congestive heart failure. Common signs of heartworm disease include: chronic coughing, easily tiring, and unusual shortness of breath.
Colorado is fortunate to have one of the lowest incidences of heartworm infection in the country. Unfortunately, the prevalence of infection has been on the rise over the last decade. Some parts of Colorado, especially the lower river valleys, are reported to have an infection rate as high as 5%. Our warmer, moister seasons over the last few years may be partly responsible for the increase in heatworm disease we are seeing in Colorado … the more mosquitos that are present, the greater the threat of infection. If you are seeing mosquitos in your area, then there is a chance for your dog to get heartworms.
Safe, effective, tasty, chewable medication is available to prevent heartworm disease in dogs. While it is true that no medication is perfect at preventing disease, the effectiveness of this drug, if properly used, does approach 100%. If you decide to use the medication, your dog will first need to have a blood test to be sure that they are not carrying adult heartworms. This test is necessary even if they were on preventative medication last year. Your dog takes the preventative medication once a month during the mosquito season.
The season on the Front Range usually lasts from April through November, or until we have a hard freeze leaving no mosquitos. If you plan to travel outside the Front Range with you dog, be sure to call us to find out how serious the prevalence of heartworm may be in the area you will be visiting.
We hope this has been useful information and will help you make an informed decision about treating your dog with heartworm preventative. If you have any further questions, please don't hesitate to call.