Heartworm disease is a very serious and potentially life-threatening disease caused by the heartworm parasite. By the time starts to show symptoms of heartworm, the disease is often in its advanced stages. This is why it is so important that your dog regularly receives heartworm prevention.

heartworm in dogs

Use our Flea, Tick and Worm Treatment Finder to identify which preventative treatments will provide your dog with complete protection against the parasites in your area.

Try our Dog Flea, Tick and Worm Treatment Finder

Try our Dog Flea, Tick and Worm Treatment Finder

What is heartworm?

Heartworm is a potentially deadly parasite that lives in your dog’s heart and nearby blood vessels and feeds on their blood. Cats can also be affected by heartworm.

How do dogs get heartworm?

Heartworm is spread through mosquito bites. When a mosquito feeds on an infected dog, it becomes contaminated with heartworm larvae. Now that this mosquito has become an intermediate host, it will eventually transfer these larvae to other pets it bites, allowing the larvae to spread through the pet’s bloodstream until they settle in their heart. A single bite from an infected mosquito can give your dog heartworm.

As it takes several months for the larvae to mature into adult heartworms, the symptoms may not show until there are a critical number of worms in your dog’s heart and lungs.

What are the symptoms of heartworm in dogs?

Heartworm symptoms in dogs typically will not show until the heartworms have matured. If you notice any signs, immediately take your dog to your nearest Greencross Vets clinic for a professional diagnosis. Many of these signs will be especially pronounced after exercise.

Heartworm symptoms in dogs include:

  • A persistent dry cough
  • Shortness of breath
  • Weakness and lethargy
  • Low stamina
  • Avoidance of physical activity
  • Poor body condition


How can I protect my dog against heartworm?

In severe cases of heartworm, your dog’s heart, lungs and other organs will be severely damaged, making it difficult to treat the disease. It is much better for your dog’s safety and comfort for you to outright prevent them from contracting this disease rather than treating it after the fact.

It is dangerous, and potentially fatal, to give your dog a heartworm preventative treatment if they have already contracted heartworm. If you are not sure of the heartworm status of your dog, please take them in for a checkup at your local Greencross Vets before you start them on prevention.

Heartworm prevention options for dogs

Puppies can begin their heartworm prevention from 8 to 12 weeks of age, depending on the preventative product. Common methods of preventing heartworm include an annual heartworm prevention option, which can be administered by your local Greencross Vets, and monthly chews and spot-ons.

Petbarn’s Flea, Tick and Worm Treatment Finder will recommend the best combination of products to provide your dog with complete protection against heartworm and other parasites.

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For more information on how to protect your pet from parasites and keep up to date with vaccinations, visit your local Greencross Vets clinic.