Untreated Canine Heartworm Symptoms

Heartworms can affect most any dog. These dangerous parasites are spread by mosquitoes and inhabit a dog's heart, causing a variety of serious complications. Fortunately, many heartworm disease cases are treatable and treated dogs fully recover. If the heartworm disease is left untreated, however, the dog will show a few indications it is in danger.

  1. Cough

    • Perhaps the most common symptom of untreated heartworm disease in dogs is a cough. According to Michigan State University, coughing typically occurs in most levels of severity, including mild, moderate and severe. The dog can cough at anytime, or only when exercising. As the heartworm disease progresses, the worms can move into the lungs, causing even more coughing.

    Exercise Intolerance

    • As the heartworm disease gets worse, affected dogs usually experience exercise intolerance. This means that the dog can't exercise as much as it used to or simply refuses to do so. Dr. Holly Nash of Doctors Foster and Smith states that some dogs with heartworm disease will also show a sudden lack of endurance when exercising.

    Abnormal Heart and Lung Sounds

    • A dog with heartworm disease will have different lung and heart sounds than one that does not. This is due to the worms' presence in the heart and lungs. The sounds are typically muffled become of the worm population. Typically, only a veterinarian is aware of the abnormal heart and lung sounds, as a stethoscope is usually required to hear them.

    Physical Changes

    • Heartworm disease that is left untreated will cause a dog to experience physical changes. Nash states that affected dogs may develop fluid in their abdomens that give them a pot-bellied look. In addition, dogs will severe heartworm disease will develop enlarged livers, possible loss of consciousness due to poor blood flow to the brain and difficulty breathing. Dogs with severe untreated heartworm disease can also die as a result of the disease.