Symmetrical Gaits of Dogs in Relation to Body Build

1. What they did

Walks, the running walk, the trot and the pace are called symmetrical gaits, because the two feet of a pair (the two forefeet, or the two hind feet) strike the ground at even intervals. From his earlier work, Hildebrand had noticed that among wild mammals, long-legged species tend to swing the legs on the same side of the body more nearly together when walking than short-legged species do. He wanted to test this idea within a single species with a very wide range of body build: the domestic dog.

• Filming. He analysed 1410 feet of 16 mm slow-motion film of 37 dog breeds. Most was filmed for the study at dog shows in California; 430 feet came from a film institute in Göttingen.
• Gait-formulas. For each performance he calculated a gait-formula: how long each hind foot stays on the ground as a share of the stride, and how the forefeet’s footfalls are timed relative to the hind feet. Each formula averaged two to seven consecutive strides. He had 240 formulas for dogs.
• Grouping by body build. There were no measurements of leg length relative to spine length for dog breeds, so he sorted breeds by eye into long-legged, middle and short-legged groups. He left out the middle group (33 formulas for 9 breeds) to avoid errors in judging.
• Comparisons. He compared walking gaits of long-legged and short-legged breeds, looked at which dogs pace, measured how long forefeet and hind feet stay on the ground, described the support-sequences (which feet carry the weight from moment to moment), and compared dogs with other canids and other four-legged animals.

2. What they found

Dogs compared with other animals

• All 240 dog gait-formulas fell within a defined area of his graph. His 21 formulas for four other Canis species and formulas for three other canid genera fell in the same area, except one for a very slowly moving coyote and two for a semi-tame dingo straining at its leash.
• The symmetrical gaits of canids resemble those of other carnivores of similar size and build.
• Dogs do not usually walk slower than shown on his graph, and usually pace and trot no faster than a slow run, tending to break into a gallop at higher speeds.

Walking and body build

• Long-legged breeds tended to use lateral-couplets gaits at the moderate walk (the hind foot and forefoot on the same side land close together in time). Short-legged breeds tended to use single-foot gaits (all four footfalls evenly spaced).
• This difference was highly significant (Mann–Whitney U test). It was least marked at slow speeds.
• He suggests that long-legged dogs carrying or pulling loads tend to use the walking gaits of short-legged breeds, which are a little more stable.

The pace

• No short-legged dog was seen to pace, and only one used a lateral-couplets walk.
• A true pace was recorded in the Bloodhound, German Shepherd and Golden Retriever. Gaits so close to the pace that a lay observer would likely call them a pace were seen in the Bloodhound, Collie, Great Dane, Rhodesian Ridgeback, Saluki and Weimaraner. Only certain individual dogs of these breeds pace.
• Animals that pace (camelids, certain horses and dogs) are all long-legged. A long-legged build seems to let an animal support itself on the two legs of one side without its body tending to roll.

How long the feet stay on the ground

• At the walk, forefoot contacts lasted 86% to 109% of hind foot contacts (90 records); on average they were equal.
• At the pace, forefoot contacts lasted 99% to 116% of hind foot contacts, averaging 106% (17 records). Few dogs were involved, so this is tentative.
• At the trot, forefoot contacts ranged from 77% to 114% of hind foot contacts (46 records), averaging 93% in long-legged dogs and 97% in short-legged dogs. He judged the difference unlikely to be biologically meaningful, but trotting dogs probably keep their hind feet down slightly longer than their forefeet.

The trot

• Trotting formulas (80, evenly divided between long-legged and short-legged breeds) did not differ between the two groups.
• Most dogs swing diagonally opposite legs together or nearly so when trotting. Some performances were transitional towards other gaits.
• Many dogs turn their bodies slightly from the line of travel when trotting. Otherwise, the hind feet would strike the forefeet. How much this matters depends on speed and body build; long-legged animals are most prone to this interference. Many smaller mammals (rabbit, squirrel, mouse, weasel) avoid it by placing each hind foot outside the forefoot; trotting dogs instead pass both hind feet to the same side of the forefeet. He did not detect the slight unevenness in footfall spacing and timing that this causes in some primates.

Variation

• The second figure of the gait-formula usually varied by 5 to 10 points between performances of the same dog, sometimes more. This is somewhat more individual variation than he had reported for horses. In general, the smaller and more agile the animal, the more its gait varies.

3. What they concluded

• The link between body build and walking gait seen across wild mammals also holds within the domestic dog: long-legged dogs walk with the feet on each side more closely paired in time, short-legged dogs with evenly spaced footfalls.
• Pacing is a gait of long-legged animals, and only some individual dogs of long-legged breeds use it. More observation will likely add more breeds to the list.
• Many dogs angle their bodies when trotting to avoid hitting their forefeet with their hind feet.
• Support-sequences deserve less emphasis than they once received.
• He notes that dog owners recognise breed differences in carriage and leg movement, which may be worth study but are not covered here.

6. Other technologies, skills or innovations

• Slow-motion 16 mm film (64 and 72 frames per second, against normal speeds of 16 to 24) analysed frame by frame.
• Hildebrand’s numerical and graphical method for analysing symmetrical gaits, with traced silhouettes from film frames showing 13 dogs at their measured gait-formulas.