Coughing up white foam can be a sign of kennel cough, a fungal infection, bloat or bilious vomiting syndrome, according to VetInfo. If a dog has been boarded with other dogs recently, kennel cough is the prime suspect and typically remedies itself within about five days; however, other causes require medication to alleviate the symptoms.
Kennel cough is an upper respiratory infection that is highly contagious and comes on quite quickly, according to VetInfo. Kennel cough typically appears five to 10 days after contact with a sick dog.
VetInfor advises that a dog who ingests the droppings of poultry, birds or bats by scratching and digging in the dirt can develop a fungal infection that needs to be treated using medication. A fungal infection is treated on an outpatient basis.
According to VetInfo, bloat occurs when too much air is in a dog's abdominal cavity. This serious condition causes the swelling and distension of the dog's stomach, dangerously low blood pressure and possible shock. Immediate veterinary attention is required if a dog's stomach becomes distended and she is vomiting white foam.
Bilious vomiting syndrome occurs when there is a build-up of bile in a dog's stomach, causing her to vomit it out, VetInfo notes. Usually a white foam, vomiting caused by bilious vomiting syndrome can also be a light yellow color.