Check the size ratio of the ears to the muzzle. The muzzle looks a tiny bit long, but I am not certain on that.
There is one thing that , though very small, makes a HUGE difference, and that's the angle of the eyes. Hold a pencil up to the image and run it from the left point of the eye (the tear duct area) to the right point of the eye. Is the pencil truly horizontal, angleing upward or angling downward? The dog in the photo has what I see as upward angling eyes, just very slightly . In the drawing, they look to angle downward. This can change the "feel" of the character tremedously. Certianly in human portraits it is absolutely paramount to have the eye angle right spot on.