What is Heartworm Disease?
Heartworm disease is caused by the parasite Dirofilaria immitis, a type of roundworm that lives inside the heart and blood vessels of the lungs. Heartworm disease is transmitted by mosquitoes. It is a serious disease that primarily affects the heart and lungs but can also affect the liver, kidney, eye, and central nervous system, and if untreated, can cause death.
The symptoms of heartworm disease are subtle and can be easy to miss. As the number of heartworms increases, the symptoms of coughing, lethargy, exercise intolerance, lack of appetite and weight loss become more apparent. However it is best not to wait until symptoms develop since irreversible damage may have already occurred by then.
Who is at risk?
The incidence of heartworm infection increases in warmer climates. 20% of unprotected dogs may be infected in certain areas of Queensland. In a recent study, almost 9% of foxes on the outskirts of Sydney were infected with heartworm. If you do not use a heartworm preventative on your dog then he/she will have roughly a 1 in 10 chance of being infected with heartworm. All breeds of dogs can become infected. Long haired breeds are just as susceptible to infection as short haired breeds. Infection can occur at any age but because it takes a number of years for symptoms to develop the disease is not often diagnosed in dogs 3 to 8 years old. The disease is seldom diagnosed in dogs less than 1 year of age because the young worms take up to 7 months to mature following establishment of infection in a dog.
How is it diagnosed?
Heartworm disease is most commonly diagnosed using blood tests that detect the presence of heartworms. Many veterinarians run these fast, simple tests in the clinic and can give you results within minutes. Depending on the test results and the animal’s symptoms additional laboratory tests, radiographs and a cardiac ultrasound may also be recommended to determine infection and severity.
How is it treated?
The goal of treatment is to kill the heartworms without harming the patient. Fortunately, the treatment options have improved but they still have potential risks. Infected animals usually receive a series of intramuscular injections, hospitalization and then strict confinement to limit exercise for weeks. The fact is, treatment is expensive, time consuming and not without risks. For these reasons the goal should always be prevention rather than treatment of this horrible disease.
The best way to treat heartworm disease is to prevent it in the first place. Fortunately, there are numerous safe and effective preventative medications available. Heartworm preventative medications are available from your veterinarian in many forms: oral, topical, and injectable. In addition to protecting your pets from heartworm disease, many of the heartworm preventatives also protect your pet against other internal parasites. This is important because it helps prevent the spread of parasites. So not only are you getting heartworm protection for your pet but also peace of mind that your pet has not picked up parasites like roundworms that can be transmitted to other pets and even humans. Finally, before starting preventative medications on pets over 6 months of age, have your veterinarian test them for heartworm infection because serious complications can develop if an infected animal is started on certain preventatives.