When a dog's temperature goes above normal it is like millions of tiny fires are burning faster. When fires burn faster, they need more fuel. Fuel for the body's fires can come from only two places, the food taken into the body, or from the body itself. Fevers ordinarily occur during illness. Illness is a time when every calorie of fuel is needed by the dog for recovery. Any increase in fuel consumption due to fever should always come from a dog's food rather than from its body.