The ASPCA and Yahoo calculated how much it costs to own a pet . . . and it's a LOT.  Here's how much it costs for different types of animals: 

For a SMALL DOG, you'll have to pay $1,314 the first year you own it . . . and $580 per year afterward. 

For a MEDIUM DOG, expect to pay $1,580 in year one . . . and $695 a year after that. 

For a LARGE DOG, you'll pay $1,843 the first year . . . and $875 each year afterward.

CATS cost $1,035 in the first year . . . and $670 per year going forward.

Some expenses you might not think about are food, which can cost more than $200 a year, grooming, and training classes.