My colt got that patch of white on his belly this year but didnt have it last year will that patch of white get bigger do you think? I dont really know much about sabino.
I don't know, and am no expert at all on pinto "things" (solid color girl here!). However, I have a sabino roan gelding that I bred. He is a 2003 horse and he had a small star at birth. The sabino made it "bigger" but not by much. I'm wondering if your guy had narrow white marking and the sabino gene has "enhanced" it?
Like Kay said it'll probably roan out more and appear bigger
My full size QH only had a star when we got him as a early 2 year old, now as a 6 year old he's got a bigger star and a huge snip that wasn't there before:
Yes, it is more than likely from the Sabino gene, and will get larger as he ages. He may also acquire more roaning spots around his flanks. I have a deep chestnut Sabino mare who started getting a few white roany spots on her belly & flanks at 3 years old....now, just a couple years later, she has tons of it!
Here is how she looked a couple years ago.
Here is how she looked last year....much more roaning!
She has almost DOUBLE the roaning now.....but only on her belly & flank areas.