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Heartworm Disease

What you need to know

Heartworm disease is a serious condition in which the parasite 'Dirofilaria immitis' takes up residence in your dog's body, specifically in the heart, lungs and associated blood vessels. It can cause heart failure, lung disease and possibly even death, while also exacerbating other conditions. These parasites develop from larvae into adult worms that can live for five to seven years in your dog's body, and grow four to six inches long in males and ten to twelve inches in females. 


Heartworm disease is spread when an infected mosquito bites a dog, leaving behind microfilariae, which then become larvae and mature into adult heartworms. After mating with a male heartworm, the adult female discharges offspring into the dog's bloodstream, continuing the life cycle yet again. The good news is that infected dogs are not contagious.

There are four stages of heartworm disease. In Class 1, you may not notice any symptoms. Class 2 is when symptoms start to appear so you may notice that your dog is more fatigued after exercise or has an occasional cough. Class 3 symptoms will be more obvious and include a persistent cough and some trouble breathing.

Finally, Class 4, also known as caval syndrome. This occurs when there are so many worms that they block the blood flow back to your dog's heart, which requires immediate surgery as fatal if untreated. It's important to identify what class a dog may be experiencing so that it doesn't potentially develop into the worst-case scenario.

Contact us if your dog is experiencing symptoms.

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