There are many reasons why dogs cough and vomit white mucus. Gastrointestinal discomfort, ingestion of foreign bodies, gastroenteritis, parvovirus, canine distemper, etc. can all cause this symptom. In serious cases, you need to go to the pet hospital for examination immediately. This symptom is easy to occur when a dog eats foreign objects or has food poisoning. You should be careful not to let the dog eat randomly, and deworm the dog on time. Heartworm and other parasitic diseases can also cause the dog to eat. Coughing and vomiting, puppies should take precautions to avoid infection with canine distemper, parvovirus and other viral diseases.