Coughing in cats and dogs can have various causes. It can be due to respiratory infections, allergies, lung disease, heart problems, foreign objects in the airway, heartworms, or kennel cough (in dogs) to name a few. Coughing can also be a symptom of more serious conditions, so it's important to have your pet evaluated by a veterinarian if they are coughing persistently or if you notice any other concerning symptoms.