Vomiting is a very common problem in dogs and cats. There are many causes of vomiting. Primary or gastric causes of vomiting are those that are due to diseases of the stomach and upper intestinal tract. Secondary or non-gastric causes of vomiting are caused by diseases of other organs that cause an accumulation of toxic substances in the blood. These toxic substances stimulate the vomiting center in the brain causing the animal to vomit. (Anatomy of the digestive system: dog / cat)

A problem that can be confused with vomiting is regurgitation. Vomiting is the ejection of contents of the stomach and upper intestine; regurgitation is the ejection of contents of the esophagus. The esophagus is a narrow, muscular tube that food passes through on its way to the stomach. 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. The pet will often try to eat the regurgitated material. You may bring a fresh sample of “vomit” for the veterinarian to examine. The pH of vomit containing food is acid, the pH of regurgitated materials is higher. Your ability to answer questions about your pet’s activity, habits and environment will help the veterinarian decide which causes of vomiting are most likely in your pet..