A life-threatening disease found in all 50 states, heartworms can cause severe damage and even death. Worms can reproduce and live in dogs and cats for years if left untreated, causing an infected pet to be host to hundreds of heartworms. Read on to learn more about this deadly disease and how you can prevent your pet from contracting it. 1 Heartworms are transmitted by mosquitoes. This is the only way pets can contract the disease. Over 20 species of mosquitoes are capable of carrying heartworm larvae, which can get into a pet’s bloodstream through a mosquito bite. The larvae travel through the pet’s blood to the lungs and heart where they settle and mature into adult worms, then reproduce. 2 Symptoms of heartworms might not appear until the disease has progressed. It can take six months for larvae to develop into adult worms. During this time a pet infected with heartworms might not show any signs of disease. As the disease progresses, an infected dog may experience coughing, lethargy, difficulty breathing, and loss of appetite. Cats with heartworm disease may exhibit respiratory issues, vomiting, and decreased appetite. 3 Advanced heartworm disease is life-threatening. In advanced stages of the disease, dogs can suffer from lung disease, organ damage, and heart failure. Treatment at this stage is costly and can be hard on a pet’s body, which is why early detection and prevention is so important. 4 Heartworm infection is easier to diagnose in dogs than in cats. The American Heartworm Society recommends yearly heartworm testing for both dogs and cats. A veterinarian can perform a blood test to detect adult heartworms in dogs. Some might also perform a chest x-ray or an ultrasound of the heart to confirm diagnosis. Heartworm disease in cats is more difficult to diagnose, as there isn’t a standardized test. A veterinarian may use antibody and antigen tests, an x-ray, an ultrasound, or another method to diagnose feline heartworms. 5 Year-round protection is a must. Prevention is key to keeping your pet free of heartworms. In fact, the disease is nearly 100% preventable when a pet is on a monthly preventative. A veterinarian can recommend the best preventative medication for your pet.