Heartworm Disease and Prevention PDF Print E-mail


What is heartworm?

Heartworm is a 100% preventable, but serious and potentially fatal, parasite that primarily infects the hearts of dogs, cats and ferrets.


How does heartworm infection occur?

First, adult female heartworms release their young, called microfilariae, into an animal's bloodstream. Then, mosquitoes become infected with microfilariae while taking blood meal from the infected animal. During the next 10- to 14-days, the microfilariae mature to the infective larval stage 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 then 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.



heartworm cycle



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.



How do you detect heartworm disease?

Heartworm infection in apparently healthy animals is usually detected with blood tests for a heartworm substance called an "antigen" or microfilariae, although neither test is consistently positive until about seven months after infection has occurred.



How big is my pet's risk for heartworm infection?

Many things must be considered even if heartworms do not seem to be a problem in a local area.  There are currently no accurate statistics of heartworm infection cases in Beijing, but it is still a risk, especially with so many pets coming from all areas of the world that are heartworm-endemic areas. Uncared-for dogs and certain wildlife such as coyotes, wolves and foxes can be carriers of heartworms. Mosquitoes blown great distances by the wind and the transportation of infected pets to different geographic locations all contribute to the spread of heartworm disease to areas that may have previously been considered heartworm-free. The best way for easy, safe prevention of heartworm infection is to administer a year-round heartworm preventive as directed by your veterinarian.


How to I prevent heartworm disease?

The good news is that heartworm disease is 100% preventable. 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.

It is the responsibility of owners to faithfully maintain the prevention program selected in consultation with your ICVS veterinarian.


For more information about heartworm disease testing and prevention, please contact ICVS:

Tel: (010) 8456-193, 8456-1940

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