Signs of Heartworm in Your Dog

Signs of Heartworm in Your Dog

Heartworms can silently infect your furry friend and when the symptoms develop the infestation and damage is often extensive. The signs of heartworm in a dog do not appear until the worm becomes fully mature, which usually takes about six months. 

Nowadays, thanks to the progress of modern medicine, heartworm infestation in a dog is fully preventable. The condition occurs when an infected mosquito bites an infected dog and then moves on to another dog and transfers the worms. 

Preventing Heartworm in Dogs 

Preventing heartworms with monthly medications or topicals is cheaper than treating a full-blown infestation of the worms. However, even with the best preventative measures, sometimes a dog does become infected with heartworms. 

Signs of Heartworm in Your Dog 

Below are a few signs of heartworm in your dog. 

Early detection of heartworms in dog stays your best defense. However, you should still be aware of possible symptoms of heartworm in your dog. 

Here are five warning signs to watch for that might show your dog has heartworms. 

Persistent Cough

A dog with heartworms will often develop a dry and very persistent cough. The cough will often occur after only moderate exercise. The reason for the cough is that the parasites are making their way into the dog’s lungs where they can create blockages and cause discomfort. 


Is your dog exhibiting unexplained lethargy? Maybe he doesn’t show an interest in playing or going for a walk then you should be concerned. Often as a heartworm infestation becomes worse, the dog will become very tired and not be interested in doing any activity that the canine once enjoyed. 

Unexplained Weight Loss

As the heartworms spread, the dog will lack energy and lose his appetite. He might start to rapidly lose weight.

Late-Stage Heartworm Symptoms

Once the heartworms start to mature, they will take up residence through the veins and lungs of the dog causing the following symptoms:  

Difficulty Breathing

Does your dog act like he is having an asthma attack? If so, then the heartworm disease might have progressed. Fluid will start to build up around the lung’s blood vessels making it hard for the lungs to properly oxygenate the dog’s blood. 

Ribs Bulging Outward

Fluid will fill the dogs’ lungs and the animals’ chest will take on a barrel like appearance which is made very noticeable due to the weight loss. 

Additional symptoms of late-stage heartworm disease also include

  • Enlarged liver
  • Noticeable heart murmur
  • Lung noise 

If your dog is exhibiting any of the above heartworm disease symptoms, contact your veterinarian to schedule a checkup.


Back to blog

Leave a comment

Please note, comments need to be approved before they are published.