That's very true...they often don't show up for years. My Teddy Bear was diagnosed as an (approx) 8 year old. I had adopted him in 2007 and he was diagnosed in 2013. Prior to that he was seen by my vet on a regular basis and dentals done...had blood work done 8 times over that time span and there were never any irregularities.
Here is the thread about his diagnosis and treatment. He is a happy boy now and doing fantastic!
http://www.yorkietalk.com/forums/sic...ver-shunt.html