In health, food moves quickly through the esophagus to the stomach. If the muscle of the esophagus loses tone, the esophagus dilates, a condition called megaesophagus. A dilated esophagus does not effectively move food to the stomach and the animal will regurgitate food usually shortly after eating. The food may also be inhaled into the airways causing pneumonia and cough. When you present your pet to the veterinarian because he or she is vomiting, the veterinarian will ask questions in attempt to differentiate between vomiting and regurgitation and to try to determine if your pet is vomiting due to gastric or non gastric disease.
Vomiting is an active process.
The pet is apprehensive and heaves and retches to vomit. If food is present in vomit, it is partially digested and a yellow fluid, bile may be present. Regurgitation is fairly passive. The animal lowers its head and food is expelled without effort. The food brought up by regurgitation is usually undigested, may have a tubular shape, and is often covered with a slimy mucus.