My fifteen year old dog, Chase has not eaten in three days it's starting to worry me. Lately he has been eating one meal a day instead of two like he used to cause he'll take the whole day to eat a bowl. He's half Lab so he has always been a big eater. I often call him a garbage can cause he eats anything given to him. Does anyone have any ideas to why he has not been eating and if so what can I do to get his appetite back. Please help.