by Kim Lee July 10, 2019 4 min read

Heartworm diseases, if left untreated, can have fatal and irreversible consequences. As a mosquito-borne disease, humid and tropical climates like Singapore’s present the perfect thriving environments. While many pet parents are aware of its existence, only a few truly understand how deadly and scary it really is.

What is Heartworm Disease?

Potty Training 101: Housebreaking Your Dog

Heartworms are parasite worms (Dirofilaria immitis) that live in the heart (hence the name), lungs, and blood vessels of your pet and can grow up to 30cm. This disease can result in fatal and lasting organ damage and if left untreated, death. It’s not contagious from dog to dog, i.e. an infected dog will not spread this disease if he comes into contact with an uninfected dog. 

How do dogs get heartworm disease then? Through a bite from a female mosquito (if you’ve ever wondered: can dogs get mosquito bites, you have your answer!). A dog is a definitive host, which means that the parasite worms thrive and go through an entire lifecycle while living inside a dog. On the other hand, mosquitoes are intermediate hosts. They pick up larvae which mature into the infectious stage (10-14 days) and are transmitted when the mosquito bites another dog. From there, the larvae grow into adult heartworms (about 6 months) and can live in dogs for 5-7 years! 

Because heartworms have such a long lifespan and the disease is so easily transmissible, dogs who are seemingly healthy can suddenly show signs of heartworm disease.

Detecting Heartworm Diseases

Potty Training 101: Housebreaking Your Dog

Heartworm disease is a silent killer because symptoms are only more notable as the condition progresses. Depending on the severity (which is reliant on the number of adult worms in a dog’s body and activity level), the symptoms exhibited by a dog varies.

Mild heartworm infestation: your dog likely only has a couple of heartworms. For sedentary dogs, symptoms include a mild and occasional cough, but mostly remains symptom-free.

Moderate heartworm infestation:If you have an active dog, then even a couple heartworms can exacerbate the condition to the equivalent of a dog with a lot more worms. Signs range from cough, exercise intolerance, and abnormal lung sounds. 

Severe heartworm infestation:This stage of the disease definitely takes a toll on dogs - their hearts are clogged with heartworms which causes symptoms that mimic those of congestive heart failure, and also include frequent coughs, fatigue, and fluid retention. More serious consequences tend to follow. 

If you suspect or catch any worrying and/or abnormal behaviour, bring your dog to the vet immediately. A blood test will be conducted to check for visibility of heartworm proteins and results can be obtained rather quickly (usually same day).

    Treating The Disease

    Potty Training 101: Housebreaking Your Dog

    Fortunately, when detected early, heartworm disease in dogs can be treated successfully. For mild to moderate cases, dogs will have to go through a couple of injections to obliterate the heartworm population. For more severe cases, treatment is a long term plan and may require long term medication. During the treatment period, it’s prudent that exercise is restricted to prevent unnecessary excitement which could open the floodgates and clog the blood vessels with dead worm fragments.

    How to Prevent Heartworms in Dogs

    Potty Training 101: Housebreaking Your Dog

    As always, prevention is always the best cure, and thankfully heartworm is easily preventable in dogs! That said, preventive methods should be applied as early as possible and consistently.

    Preventive Medications

    Heartworm prevention medicine for dogs include oral tablets, topical applicators likeRevolution’s, or annual injections. If your dog is more than 7 months old, you’ll need to send him for a blood test before starting on any heartworm preventive since these medications are rendered useless if your dog is tested positive for heartworm. If he is less than 7 months old, then this is not necessary - preventives can be used immediately. While highly effective, your dog can still be infected - though, percentages are kept to a minimum. Once you’ve started on any heartworm preventives, you’ll need to keep at it consistently. Any lapse in the routine is the golden unprotected window for an infection to take place. 

    Control the Environment

    Since mosquitoes are the transmitters of this disease, keeping your home environment clear of potential breeding grounds will help greatly. Remove containers that can collect and store stagnant water, keep the grass short and rake up fallen leaves (if you have a lawn). Use water bowls that keeps the exposed area to a minimum but still allow easy access for your dog - Love Pot's Water Bowlsare good examples!

    Regular Checks

    Schedule routine visits to the vet to ensure that your dog is free from heartworm disease and that the preventives are working. At the minimum, your dog should be tested annually, but the frequency can be amped up if your choice of preventive is oral or topical - your vet will be able to advise you on the appropriate frequency.


      Kim LeeKIM LEE
      Kim is an avid dog lover, serial guac and chips eater, and thrill seeker - all in one body. Currently chillin’ with her dogs.

      Leave a comment

      Comments will be approved before showing up.


      Also in Dog Talk

      The Ultimate Guide to Dog Cafes in Singapore
      The Ultimate Guide to Dog Cafes in Singapore

      by Good Dog People September 24, 2020 4 min read

      Itching to bring your furkid out for a nice brunch or dinner date? Want to throw a puppy...

      Dog Injury 101: How to Care for Injured Dogs
      Dog Injury 101: How to Care for Injured Dogs

      by Good Dog People September 17, 2020 3 min read

      What should you do if your dog gets injured? What can you do if your dog...

      All About Dogs in Dementia: What You Can Do For Your Pooch
      All About Dogs in Dementia: What You Can Do For Your Pooch

      by Good Dog People September 10, 2020 4 min read

      One of the most common problems that senior dogs face, pet dementia can be a subtle yet highly...