Boy and a literal Watchdog explore in a kind of crazy world

A boy somehow finds a dog, which actually has a clock on it's side. They somehow get into this world. Parts of it are all numbers, or letters, and everything is kind of switched around. I remember one part that he tries to go up stairs but they never end. Sorry it's not much information! I read it a long time ago.

Could it be The Phantom Tollbooth, perhaps?

Yes that's totally it, thank you soo much!

You're very welcome. That watch-dog is a very memorable one. :)