Dogs develop coughs because they catch viral and bacteria infections and breathe in dust, fungi and other pollutants, says WebMD. One very common reason for dogs to cough is kennel cough, a deep cough that's followed by gagging. Dogs pass kennel cough from one to another.
Though kennel cough is very contagious, it is not serious in an otherwise healthy dog, says WebMD. Most dogs get over it in about a week or so and may not even need medication. Fungi and yeasts are other reasons for a dog to catch a cough. Veterinarians prescribe medicines to clear up fungal coughs.
Dogs also cough when they contract heartworm, according to WebMD. This is a serious disease spread by mosquitoes. The condition is avoidable with medication taken once a month or a vaccination that is good for six months. Distemper also causes a cough and is serious, but it is preventable with a vaccination.
Heart and lung problems also cause a dog to cough, states WebMD. In the case of heart disease, a vet can put the dog on medication, suggest an exercise regimen and prescribe a new diet. Dogs also catch pneumonia or bronchitis and suffer other infections in their bronchial passages. Lung cancer is another reason for a cough, though rare.