Be careful not to give your dog artificial sweetners.  One of them, Xylitol, is toxic to them.  It’s used in sugar free gum and some baked goods.

Xylitol enters the cells without insulin which can cause your dog to become hypoglycemic, i.e. have low blood sugar.  If left untreated, it can affect the liver.  Treatment includes an IV to reestablish glucose levels in the blood and watching the liver enzymes to ensure the liver has not been affected.

So if you notice your dog becoming very lethargic a few hours after eating baked sweets, check the label to see if this might be the problem.