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Morphological Difference Between a Dog & a Grey Wolf

Domestic dogs likely derived from wolves some 15,000 years ago. The two animals are thus closely related and occasionally interbreed, although the dog's long association with human beings and their methods of selective breeding have resulted in variety in physical appearance. Certain breeds, such as Pekinese, have obvious differences compared with a big Alaskan gray wolf. For more visually similar comparisons, certain clues can often separate out the wild ancestor from the domesticated descendant.

Size
- Gray wolves are heavier than most, but not all, domestic dog breeds.
  
  The various subspecies of gray wolf display substantial variation in size; like most animals, they tend to exemplify the ecological rule that animals at higher latitudes are larger than those closer to the equator. Thus the Arabian and Indian subspecies (which some believe may be different enough to warrant their own species classification) tend to be lighter and shorter than their more northern cousins of mountains, steppe, taiga and tundra. The largest gray wolves of northern Eurasia and North America may measure 3 feet at the shoulder and over 6 feet from nose to tail and weigh better than 170 lbs. Selective breeding means dogs come in a far vaster array of sizes. The smallest domestic dogs, such as Yorkshire terriers, may be under 10 lbs. as adults, while the largest, like St. Bernards and English mastiffs, can well exceed 200 lbs. in weight.
Head
- Gray wolves have robust teeth with big canines and shearing carnassials.
  
  The head of a gray wolf tends to be broader than that of a domestic dog; the brain case of the wolf may be 30 cubic cm larger. Wolves tend to have more subdued foreheads than dogs and, in general, longer and thicker muzzles. They also usually have far stronger jaws and heavier dentition than domestic dogs, with canine teeth over 2 inches in length and robust carnassials for slicing flesh and crushing bone. The ears of gray wolves are large, furred and erect, while dogs have a great diversity in ear shape. Many domestic breeds have floppy ears.
Build
- A wolf's long legs give it substantial height at the shoulder.
  
  Another notable difference between gray wolves and dogs lies in the chest region. Wolves have relatively narrow chests, while dogs tend to have broader ones. The narrowness of the wolf's reflects its cursorial, or running, nature. The legs lie close together, allowing the trotting animal to place its hind paw in essentially the same spot as the forepaw ahead of it. A domestic dog's tracks tend to show fore- and hind prints on the same side of the body next to one another. Wolves are usually taller than domestic dogs, even those that outweigh them.
Paws
- Dog tracks often splay out more than those of a wolf.
  
  Northern gray wolves have huge paws, an adaptation to snowy winters: These snowshoe-like feet allow them to walk atop the crust, often giving them a distinct advantage when pursuing deer or moose. A wolf's pad may be over 5 inches long and nearly as wide. Big dogs also have large feet, but their tracks can sometimes be distinguished from those of similarly sized wolves by the more splayed angle of their toes. A wolf print, like that of many wild canids, tends to be more obviously forward-aligned, with straighter toes.

Animals & Science