To go to the Vet is why I purchased.  Although I have two Yorkies, I purchased one for each of them because they each like their own space.  Actually, it's really easy to pull one behind and push one in front.  I got the largest size for comfort and height.  They lay flat underneath my desk and they take naps there. When laying flat, I cushioned the bottom for comfort and attached corners so doesn't flap forward.  Now it's perfect.