When they bite, mosquitoes can transmit heartworm infection. And those heartworms can wreak havoc on your dog or cat. These parasites can severely and sometimes fatally damage the heart, lungs, and blood vessels. Some pets may not show any signs of infection; in those that do, symptoms can vary widely.
In dogs, signs of heartworm disease can range from coughing, fatigue, and weight loss to difficulty breathing and a swollen abdomen (caused by fluid accumulation from heart failure). Canine heartworm infection can also lead to a life-threatening complication called “caval syndrome” (a form of liver failure); without prompt surgical intervention, this condition usually causes death.