Puppy Eye Color Change. Both dogs and cats can experience eye color changes in their lifetimes. Sadly, however, your puppy’s eyes will start to change color as it grows older.

Their eyes can go from blue to grey to blue again, or they can change from blue to grey to brown over the course of a month or so. Once they have reached full maturity, their vision is as good as it will ever be. You should be able to notice a subtle change in their eye color from week to week.