On the physical side, the German
Shepherd Dog is of medium to large size, with enough weight to be effective
as a
herder or a patrolman, but not so big
as to be cumbersome.
The same ancestral autosomal recessive mutation for the progressive rod cone degeneration (prcd) form of progressive retinal atrophy (PRA) is found in the American Cocker Spaniel, American Eskimo Dog, Australian Cattle Dog, Australian
Shepherd, Chesapeake Bay Retriever, Chinese Crested Dog, English Cocker Spaniel, Entelbucher Mountain Dog, Finnish Lapphund, Golden Retriever, Kuvasz, Labrador Retriever, Lapponian
Herder, Norwegian Elkhound, Nova Scotia Duck Trolling Retriever, Poodle, Portuguese Water Dog, Silky Terrier, Spanish Water Dog, Stumpy Tail Cattle Dog Swedish Lapphund, and Yorkshire Terrier.3 This list continues to grow
as more breeds are discovered with the same defective gene.