This is such a nice drawing! beautiful shading and clear lines are pleasure for the eyes! Sorry about Marlow. He must have been a beloved member of your family. I've read other people's comments, and I totally agree with the point that you could push the gesture, making Marlow seem more excited to play! Speaking of the design, I love the idea that you let Marlow hold a surfboard and wearing swimming shorts; that really shows how much he loves water! Though it seems to me that the surfboard is a bit too small for him. Maybe you could try increasing the size of it to fit the his size. Also, I want to point out that the tongue, the eyelids, the fur on the back of his head, and the ears seem stiff to me. They are supposed to be the soft parts of the body; maybe you could use smoother shading to give them softer looks. Last, the human nails on his paws seem a bit odd to me. Looks like you incorporate human hands and animal feet. It might be better to make the design of his paws conform to his feet. Overall, my suggestion is to give the design a tint of consistency and the sense of reality to involve the audience.