Heartworm

What is heartworm?

Heartworm is a parasitic worm that your pet gets infected with via a mosquito bite. An infected mosquito injects a larval stage of the worm under the skin. The larvae then mature in your pet’s organs for approximately six months, traveling around the body until they get to the heart and blood vessels. The matured worms (now adults) breed and produce microfilaria (baby worms) in the bloodstream. The microfilaria can then be drawn up by another mosquito when it feeds on the pet. The microfilaria then mature into larvae in the mosquito. This infected mosquito can then pass the heartworm to another dog and thus the cycle continues.

What are signs of heartworm?

Dogs

Since heartworm is a slow onset disease, it is nearly impossible to tell if anything is wrong with your dog initially. This disease can take months or years even before signs are obvious. When they do show symptoms, your dog could already have a large heartworm burden.

The worms in the heart interfere with the movement of the heart valves, causing the blood vessels going to the lungs to become basically blocked (with worms). This puts the heart under immense stress, leading it to becoming enlarged and exhausted.

Early signs include: shortness of breath, loss of stamina/fitness, a dry cough that seems to linger

In severe, later stages of disease: breathing becomes difficult, the abdomen may swell with fluid, the dog becomes lethargic and lose weight and their appetite

Given that the signs are hard to detect until severe disease, prevention is the best option.

Cats

Early on, cats show very few clinical signs. They can develop slight lethargy or a cough. Unfortunately, sudden death is more common in cats with heartworm as it often goes undetected and untreated.

It only takes one to two adult heartworms infecting your cat to be potentially fatal. Again, prevention is the best option.

How is heartworm diagnosed?

A simple blood test at the veterinary clinic reveals infection of heartworm.

How common is heartworm?

The prevalence in Australia is poorly understood, but what we do know is that wherever there are mosquitoes, there is potential for heartworm. We have had a few positive heartworm cases recently in Coonabarabran. This tells us that it is in the area, so we are strongly encouraging testing and prevention.

Can heartworm be treated?

Yes, however prevention is far better than treatment.

Treatment for heartworm is risky, long term (it usually takes a year to treat), difficult and expensive. If left untreated, the disease is fatal.

How do you prevent heartworm?

There are many options available. If you dog or cat has not had heartworm prevention for more than six months, they will need a blood test first to make sure they are not already infected with heartworm before resuming prevention. Prevention should begin at six to eight weeks of age.

Below are some prevention tables for you to peruse and pick what prevention will work best for you and your pet.

As always, please do not hesitate to call us at the clinic for more information or to book your pet in for testing and starting prevention.