I made some rough drawings to use for reference, because I don't really know enough about dog anatomy to draw something I'm sure of for orthographs.
I have also been looking at lots of photographs - I'm basing this on a Rottweiler.
This is my progress on the legs. I will add more edge loops to support the joints.
I'm going to start work on the head, next. I am looking at photographs and anatomical drawings for reference, and will make different drawings for orthographs.
I'm enjoying having a reason to spend extra time with my own dogs, although they are chihuahuas, it's still useful!