4. Respiratory problems
If a dog develops lung cancer it will show signs of respiratory problems. Some common symptoms include wheezing, coughing, and shortness of breath. Lung cancer is not very common in dogs, and when it does develop, it’s usually later in the dogs life. Dogs with short snouts are more likely to suffer from breathing problems, but they will usually not be due to lung cancer, but rather due to them having a flattened face.