Heartworm disease begins when a mosquito bites an infected animal, ingests the blood, and then bites another animal, such as your pet. This transfers the worms from the previous infected animal into your cat or dog. Fortunately, treatment is possible. The sooner you notice signs of heartworm, the higher the chance for successful treatment. Here are 5 symptoms of heartworm disease to look out for. 1. Dry cough Heartworms affect the lungs and can make it difficult for your pet to breathe or exercise. This can lead to a consistent dry cough. You may notice your pet go into a coughing fit after playing or exercising. A dry cough is one of the earliest signs of heartworm disease and your pet may not experience any other symptoms at this stage. Contact your veterinarian immediately if your pet develops a cough. 2. Lethargy Heartworm can cause your pet to tire easily and make it difficult to engage in low-energy activities. Take note of how active your pet is and be aware of any drops in energy levels. If your pet hesitates to play or go outside, then this could be a sign of disease. Lethargy can be a symptom of various conditions, so it is important to work with your veterinarian and find out the cause. 3. Swollen Belly and Bulging Ribs The middle-stage symptoms of heartworm disease include a swollen belly and bulging ribs. Mature heartworms can live in the lungs and veins of your pet, which can cause blockages and fluid buildup. Your pet may also lose weight. The fluid buildup and weight loss can cause your pet’s belly and chest to swell or the ribs to bulge. 4. Difficulty Breathing A symptom of an advanced case of heartworm disease is difficulty breathing. Once your pet’s lungs have been infected by adult heartworms, respiratory problems can begin. The heartworms cause fluid to build in the blood vessels in the lungs. This makes it difficult for your pet to receive oxygen. If this occurs, your pet may start taking shallow, rapid breaths. 5. Fainting A late-stage symptom of heartworm disease is fainting. After a significant amount of heartworms have infected your pet, fainting can occur. This is due to a blockage of blood flow in the heart. Contact your veterinarian immediately if your pet experiences this warning sign. Heartworm disease can be a dangerous condition for your pet. Luckily, it is preventable and can be successfully treated. Talk to your veterinarian about year-round preventative medication to keep your furry companions protected from these pests. Be sure to bring your pet in for routine heartworm testing as well. With both preventative treatment and regular exams, your pet will be safe for years to come.