which dog is the smallest size in the world?

There are quite a few small and toy sized dogs, both purebreed and mixed. What dogs have you seen that you like? You should check out a book on dog breeds or go on line and check them out. You want a dog you like and that has a personality that will fit with you and your family's. A pet is a big decision that you will live with for 10-15 years or more! Small pets may not need as much room as a big dog, but they still need the time, attention and care. Good luck with your choice!

No, I don;t want to know because I don;t like to keep pet animals.

Probably a Chihuahua? That should be the smallest dog available. Of course there might be really small sized Chihuahuas. But these dogs are terribly undersized and might have health issues.

I have a mini peke, she is only 5lbs and that is quite small for a dog but I have seen smaller. You might want to do a search on Cha Cha and see what answer they come up with.