Heartworm Disease and Prevention

Heartworm disease is a serious and potentially fatal condition caused by parasitic worms living in the arteries of the lungs and occasionally in the right side of the heart of dogs, cats and other species of mammals, including wolves, foxes, ferrets, sea lions and (in rare instances) humans.

How Heartworm Happens: The Life Cycle

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First, adult female heartworms release their young, called microfilariae into an animal’s bloodstream. Mosquitoes then become infected with microfilariae after biting an infected animal. During the next 10 to 14 days, the microfilariae mature within the mosquito. After that, the mosquito bites another dog, cat or other susceptible animal, and the infective larvae enter through the bite wound. It takes a little over 6 months for the infective larvae to mature into adult worms. In dogs, the worms may live for up to 7 years. Microfilariae cannot mature into adult heartworms without first passing through a mosquito.

What Are the Signs of Heartworm Disease?

For both dogs and cats, clinical signs of heartworm disease may not be recognized in the early stages, as the number of heartworms in an animal tends to accumulate gradually over a period of months and sometimes years and after repeated mosquito bites. Recently infected dogs may exhibit no signs of the disease, while heavily infected dogs may eventually show clinical signs, including a mild, persistent cough, reluctance to move or exercise, fatigue after only moderate exercise, reduced appetite and weight loss. Cats may exhibit clinical signs that are very non-specific, mimicking many other feline diseases.

How Do You Detect and Prevent Heartworm Disease?

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Heartworm infection in apparently healthy animals is detected with a simple blood tests.  A heartworm tests uses just a few drops of blood and also tests for lyme disease and ehrlichiosis (another tick borne disease). Heartworm prevention is safe, easy and inexpensive. While treatment for heartworm disease in dogs is possible, it is a complicated and expensive process, taking weeks for infected animals to recover. There is no effective treatment for heartworm disease in cats, so it is imperative that disease prevention measures be taken for cats. There are a variety of options for preventing heartworm infection in both dogs and cats, including monthly tablets and monthly topicals. All of these methods are extremely effective, and when administered properly on a timely schedule, heartworm infection can be completely prevented.