As an avid reader I love to try different authors and time periods. I just finished reading the reviews of this book and ordered it from Amazon. A Dog's Purpose is also a great book to read. It even has a GSD in it and the laugh/cry ratio is enormous.
The movie looks cute. I was disappointed to learn it is a cartoon though (sorry I guess animated feature is the correct term). Parts of the book were hilarious, but it reflects some of the things people did with their dogs in those days, which aren't considered correct now.
I finished the book and enjoyed it. Although it is not for everyone I found it to be a period piece and you have to take that into consideration. The writing style was exquisite. Yes there are chapters on "liquids and solids" as well as in depth writing on the "sexuality of the canine". We all know how important solids are, just look at the topics in the health forum. As far as the sexuality of the canine and seasons i.e. heat, just go the breeders forum and check that out. There was nothing vulgar or unnatural in this story, just a bond between and man and his GSD. I would suggest it for a quick read.