Here is the structure underneath a skin dog. When you know what the bones are and their proportions, then you know also why and how to draw a dog.
Skeleton = fixed proportions
Rib cage and pelvis
Spinal chord (convex)
"Upper" spinal chord (concave)
"Hands" and "feet"
"Fingers" and "toes"
...and the external picture (from wikipedia):
Each species has its own.
For instance in the ideal dog the length of a whole leg is equal to the height of the its upper body.
Alternatively for an Italian Corso (here left), the proportions will vary and so on...
(picture taken for educational purposes from www.mysticvalleycanecorso.com)
Furthermore, it is also important to localte the pivot points (places of leverage, places where the movements are created).
I have watched how to draw dogs movie clips on youtube where you don't learn what you expect to....
You merely see people with drawing skills at work. You don't see the subtilities of drawing...
For this reason I would not stop recommending this teacher here. Drawing with confidence is the essential first step to drawing anything.
So start from the beginning!
Sometimes I think the Internet is NOT the proper medium to learn something which require patience and time. There is a hurry to jump steps.
Perhaps the Internet is a way to get the information.
But then it's wise to disconnect completely .
(ideally one could go to a log-house in a forest, in perfect isolation, and stay there for three months...John Belushi's best performace can give you an entertaining, enriching example of what I mean )
This is a book for children, full stop. Where do you want to start from if not from the very beginning?
Remember that Picasso's quote that I write from memory:
"When I was a kid I used to draw like an adult. It struck me when I was old that I had to draw like a child!"
Then move on to something more detailed like this other kid book.
Christian Albrect Dürer, knight in a northern forest, engraving, 1513
Then look at more dogs than you can from real.
Also old paintings, engraving especially,
and so on...