April is Heartworm Awareness Month
Every three years, the American Heartworm Society (AHS) gathers data from thousands of veterinary practices and shelters to review the average number of heartworm-positive cases per clinic. The most recent heartworm incidence map from 2019 shows heartworms are present in all 50 states https://d3ft8sckhnqim2.cloudfront.net/images/incidence-maps/2019-AHS-Incidence-Map.pdf
Heartworm disease is diagnosed mainly in dogs and, less frequently, in cats and ferrets. Heartworms also live in other animal hosts such as wolves, coyotes, foxes, California gray seals, sea lions, and raccoons. It is transmitted through mosquito bites and is dependent on a climate with adequate temperature and humidity to support mosquito populations. In California, winter rains, gray water systems, irrigation, tree planting, commercial, and real estate development, interstate pet movement, and the introduction of non-native mosquitoes, e.g., Aedes aegypti – https://cdphdata.maps.arcgis.com/apps/webappviewer/index.html?id=57367199287a4d18a2cecf107854255b – have all contributed to increased risk from heartworm disease.
Some heartworm-positive pets may not show any clinical signs of disease, others may have coughing, vomiting, or lethargy dependent on the extent of the disease. For some, the disease can cause heart failure or renal failure. The period between the initial infection when the pet is bitten by an infected mosquito and the development into reproducing adult worms usually takes six to seven months.
In dogs, prevention is safer and far less costly than treating the disease. Efforts should be undertaken to limit exposure to or repel mosquitos, e.g., eliminate standing water around the yard weekly, use window screens and mosquito repellant. There are many oral and topical heartworm medications available for pets that are designed to kill the larvae heartworms before they mature into the adult forms. A blood test is usually undertaken before starting a preventative program and then annually to make sure there are no adult heartworms present. Some common heartworm preventives include Advantage Multi, Heartgard Plus, Interceptor, Sentinel, Tri Heart, Trifexis, Simparica, and Proheart. Additionally, many of these monthly preventatives also have coverage for intestinal parasites like intestinal roundworms (Toxocara canis) which have an increased infection risk in Western states and can have zoonotic potential (human health impact). For these reasons, annual heartworm testing and monthly prevention are part of our routine wellness recommendations here at Wise & Wonderful.
https://www.heartwormsociety.org/images/Heartworm_Life_Cycle_for_Professionals.mp4
