1 : That shadow cast by the ear... that's what I was referring to in your Snow Leopard drawing, where the shadows were absent. Here, you used it wonderfully well to emphasise the edge of the ear. We can instantly see that the ear is tipped over and the tip is in front of the rear portion.
2 and 3 : This is something that is not noticeably wrong but you need to careful with in the future. Line 2 marks the angle of the eyes and, unless the dog is twitching its nose, all other features need to conform to that angle. Your nose and mouth (Line 3) are slightly tilted anti-clockwise. As I said, it's not very noticeable, but if the angles differed more, it would definitely be a problem.
4 : These two vertical lines mark where Mr Fritz's stop would be. That's where the muzzle rises up into the forehead, and where the two sinuses enter the head. The hair to both sides will fall into a valley and meet with the tear ducts in the eyes. What you've drawn isn't wrong but Fritz's' off-centre markings cause some confusion. I'm suggesting that if you emphasise the stop, we (the viewers) will understand where the centre between the eyes actually is, rather than the marking suggesting they are off to our right.
5 : Superb! Just keep doing what you're doing. The only way to draw white hair is to draw the shadows between the hairs. Actually, it's the only way to draw any hair but I haven't time to discuss that huge subject here
