The dog in this 15th Century German text appears worried as he looks up plaintively to the man holding his leash. He is among some people who are worshiping the beast. The image is part of one of 36 painted miniatures contained in this book illustrating the apocalypse. The dog seems to know something is not quite right here. Unfortunately for him, being on the leash prevents him from doing much about it.
The book is part of the manuscript collection of the New York Public Library. More information here