Quote Originally Posted by SmokinDVM
How old?
Any signs of neurological deficits?

I've got to leave for work, I'll get back here and answer more later, but it's probably not a huge concern especially if it's young and has no other signs of problems. Very common problem in chihuahuas. Most of them I see have some degree of open fontanels.
he's only a year old and probably the smartest dog i've owned.