"Rest In Peace my dear dear Fuller I love you more than you know," the 20-year-old actress wrote alongside a sweet pic of the pup. "You've been my protector and best friend since I was a little girl and I wish the end didn't come so abruptly but I know you're at peace now. I love you I love you I love you you will forever be missed."
Moretz shared another snap of Fuller on Wednesday, writing, "The last picture I ever took of my little boy, I love you endlessly. I miss the warmth you brought to our home and our hearts. Not a day will pass that I won't think of you and thank you for the joy you gave us. Rest In Peace my love."