All you need to know about canine heartworm disease

October 18, 2011

Heartworm disease

Heartworm disease is caused by parasitic worms and it is a fatal condition as these inhabit in the right side of the heart and lungs arteries of dogs, foxes, cats, wolves and some species of mammals too. Heartworms belong to the family of nematodes and the particular nematode responsible for causing this serious disease in both dogs and cats is called Dirofilaria imminitis.

The infection in dogs takes a few months and then establishes itself completely in a duration of six to seven months. These worms can reach up to a height of three feet. Learn all about the fatal disease that can conquer your pet dog or cat.


Heartworm infection is primarily caused by mosquito bites when it sucks the blood of an infected dog. The infected blood contains microfilariae. In a time of two weeks these microfilariae reach the larval stage. When this mosquito bites the other dog, the infective larvae is introduced into the blood stream of the other dog and it gets infected and then the cycle goes on. The natural cause of this fatal disease is the mosquitoes.


The signs of the disease might not appear but this depends on the size of the roundworms. The symptoms can also appear in a span of six months of infection. Majority of cases have shown the symptoms after one or two years of infection. The symptoms include lethargy, loss of appetite, coughing, tiring quickly during the exercise, fever and weight loss. These signs may typically vary and the disease might reach a certain higher level before diagnosing or otherwise the signs might point towards this infection with no actual detection. In acute cases, the lungs and heart can get damaged severely leading to heart failure if the treatment is not initiated.


Detecting the disease in its initial stages can be only done through a blood test. The veterinarian does a simple diagnostic test to detect the minute microfilariae in the infected blood sample of the dog. In general, microfilariae are not seen in the test results; long and adult heartworms are definitely traced in the blood samples. To confirm the infection, echocardiogram, X ray and other lab tests are taken up. The blood test caused by female worms detects the antigens accurately.

Frequently Asked Questions

i) What is it?

The disease is caused by roundworms, particularly Dirofilaria imminitis. These grow and take a height of about 6 to 14 inches and attack the right portion of the heart.

ii) What does it do?

The accumulation of these worms in the blood retards the circulation of blood in the body and endangers the life by damaging the heart, liver, kidneys and lungs of the dog. A great deal of damage is done before the disease is diagnosed. If only a few worms are the inhabitants in the body of the dog, it can lead a normal life. But if the worms increase in numbers then the disease can prove fatal and the dog might suffer from constant coughing, labored breathing, weight loss and in acute cases the dog might faint. Heart failure and death are the ultimate ends.

iii) Can infected dogs be treated?

If the disease is verified in the early stages, then the dogs can be treated successfully. An arsenical drug is given with the help of administered injections to the dog to kill the worms. After the injection is administered, the worms get killed and are sent to the lungs as the blood flows. They accumulate in the blood vessels here and are decomposed and then absorbed by the body in a few months. Though, the risks involved in the treatment cannot be avoided. To avoid the complications by giving the dog a laboratory and physical examination before the treatment begins. Exercise should not be done at all. When the heartworms are washed away, another drug should be given to prevent the microfilariae spreading their chain as these are not affected by the drug that was used prior to kill the adult worms.

Things to avoid

Homeopathic care, nutritious and well balanced diet is required while minimizing the exposure of the dog to vaccines and drugs should be avoided. Spread oil sprays to keep the mosquitoes at bay as they play the prime role in spreading the disease. A low intensity drug can help the larva to die in the initial stages before they reach to adult stage.

However, there are a lot of mysteries that are still unresolved and the scientists are working on it.

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