Sorry to hear of your loss. Cute quilt! Are you going to thread paint the hair on the dog in blue tones? But after looking closer, the blue lines are fabric? Maybe lines of white between the blue to emphasize the hair. Love the way it looks, as if it is flowing.
Maybe use white thread with plain hearts here and there around the upper part of the dog in different sizes and angles, like love radiating from him, and use the red heart on a label saying "In loving memory of ..." or something like "Dogs leave their paw print on our hearts. Made in loving memory of ...", etc. (All of a sudden, I miss my baby. Funny how they can become a part of you.)