To examine the organs of digestion one needs to study the appetite and manner of taking food and drink. A healthy animal has a good appetite. Loss of appetite does not point to a diseased condition but comes from a variety of causes; some might be physiological. Excitement, strange surroundings, fatigue and hot weather, may all cause loss of appetite.

The nutrients and macromolecules present in food are not immediately accessible to the cells. There are a number of processes that modify food within the animal body in order to make the nutrients and organic molecules accessible for cellular function. As animals evolved in complexity of form and function, their digestive systems have also evolved to accommodate their various dietary needs.

Sometimes depression, fever, weakness, stomach disorders or difficulty in swallowing also cause diminished appetite. A few times there is a desire to eat abnormal things like roots, grass, soil due to chronic disturbance of nutrition, and it is variably linked to one’s psychological aspects also. In times of inward happiness one tends to binge more on food but in times of turmoil and tension one loses the desire to eat even if hunger persists. At times, thirst faces this imbalance as well. Especially in times of crisis or shock, your mouth goes dry. So, hunger loss can not only be connected with appetite loss due to disease; there are profound psychic disturbances also attributing to its fall.