People love their pets. And while you may think Fido is your little “fur baby,” big food companies see your pet as a potential money maker. According to the American Pet Products Association, retail sales of pet food have nearly doubled in the U.S. in the last decade, to more than $30 billion. That’s led some major food companies to buy up pet food businesses, including the cereal company General Mills, which last year bought Blue Buffalo Pet Products for $8 billion.