Recognizing Heartworm Dog Symptoms Early

Heartworm dog symptoms escalate as the parasite invades the bloodstream, heart muscle, arteries, veins and valves. Noticing heartworm symptoms as early as possible will allow you to seek aggressive treatment that saves your dog's life.

Growing more than a foot long, heartworms infect dogs that have been bitten by mosquitoes carrying heartworm larvae. Some dogs may have as many as 250 heartworms in their body.

Progression of Heartworm Infestation

Proliferating in colonies, heartworms cause catastrophic damage. Heartworms impede blood flowing out of the heart into the lungs, causing fluid build-up. To compensate, the heart muscle thickens and works harder, but circulates less blood. Heartworms also impede blood flow into the heart, causing blood to back up in the main vein and abdomen. Heartworms impair heart valve functioning, too, causing blood to pool in the main vein and liver. Finally, blood cells attach to heartworms in the bloodstream, forming clots that cut off blood to organs.

Symptoms of Advancing Heartworm Disease

Heartworms cause the following symptoms:

  • Soft cough
  • Difficulty exercising
  • Lethargy
  • Bloody sputum
  • Reduced appetite
  • Weight loss
  • Pot belly
  • Anorexia
  • Rapid breathing
  • Shock
  • Brown urine
  • Blindness
  • Lameness
  • Seizures

Diagnosis and Treatment

Blood tests confirm the presence heartworms in your dog's body and X-rays show any harm they have done. Treatment is difficult and risky, but critical to your dog's survival.