Food is eaten normally, passes through the pharynx at the back of the throat normally and enters the gullet (oesophagus).Passage through the oesophagus into the stomach is prevented and the food accumulated in the lumen of the oesophagus is passively brought up and passes out through the mouth. The animal does not actively contract it's abdominal muscles during regurgitation as it does when vomiting. The food brought up usually adopts a "sausage" shape and it consists of food mixed with saliva. It has an alkaline pH because it has not reached the stomach where there is an acidic environment. Sometimes animals attempt to eat the regurgitated food. Some of the food can be inhaled into the lungs causing aspirations pneumonia. (see also pharyngeal retching).