If you have a small dog, you know much you love the little stinker. But, how much are you spending to meet its needs? A small dog isnt the most expensive pet in the world, but it certainly will cost you money. Every year, you can expect to spend $400. During the first year, you can expect to spend $780. With the long life expectancy of a small dog, an average of 14 years, that little dog adds up big- to the tune of $5,980.