I had to laugh when I read that Kim was asking if it was sanitary to sleep with her new yorkie.  
 
"How do u guys feel about dogs sleeping in the bed with you? Is it sanitary? My personal feeling is no, but I'm having a debate," she asked her followers on Twitter." 
Is she worried about the Yorkie getting something, or it making her sick? 
 
 
Anyway, according to this site 
Kim Kardashian and Kris Humphries Get a Puppy! | Gather "The dog definitely didn't look like a puppy, and it's very possible that the couple adopted him/her from a local shelter."  Petco does have adoptions, so it's possible she adopted him there, if that's true,  all I can say, is "Way to go Kim!"