This is a Dog by Ross Collins

Ross Collins set out to write an animal book for young children. His book was going to be called My First Animal Book but some how his dog became involved. Dog had a powerful crayon and so the mischievous pup takes over every page - oh no! This book is such fun. Wait until you see the giraffe page - it's certain to give you a huge laugh.

Uh-oh! An excitable (but very loveable) dog has found his way into this First Animals book and he will NOT let any of the other animals take their turn. Dogs are far more important, after all! And when the other animals get angry, this dog comes up with a very cunning plan to outwit them . . . Nosy Crow

This is a Dog was the 2021 Bookbug winner. Here is a video where you can see the whole book and hear Ross Collins talking about this idea behind his book.

I do like books which appear to be scribbled on by their characters. Here are two others:

It is also fun to read aloud books with characters who interrupt the story: