Reasons : to get attention frm their owners, boredom, stress, anxiety or having being punished for bad behaviors , they have been punished for having defecated in the past and attempt to clean up out of fear to be punished again, over feeding leading to large concentrations of undigested matter in the feces. For puppies they taste everything and discover that feces are edible and perhaps tasty, especially when fed on high fat content diet. Also because they are hungry, such as when eating routines are changed, food is withheld, or nutrients are not properly absorbed.