Differences in the Behavior of Landraces and Breeds of Dogs - Genetics and the Behavior of Domestic Animals - page 210

or double flights, such as greyhounds, would be pulled off balance by their
harnesses because all four feet leave the ground during the flight. The partic-
ular gait that a dog performs is predisposed to and limited by skeletal and
muscular morphology.
All dogs on a sled dog team should have identical gaits and strides.
Ideally, they should move together, each pair a mirror image. Dogs differing
in gait and not synchronized in their motions introduce inefficiencies in the
forward movement of the sled because the angular vectors of the harnesses
have energetic costs. In order for the dogs to run synchronously they should
have identical morphologies.

Behavior
Foraging
Modern sled dogs are captive animals. They are not allowed to forage on
their own; they are fed by their owners. Dog drivers recognize that their
dogs must be fed well in order for them to perform well. Distance racing
dogs can burn 10,000 calories a day and the trick is how to get that much
food into a relatively small stomach. Heating food and water to body temper-
ature can reduce the amounts to be ingested. Foods high in calories (fats and
oil) are preferred. The peristaltic action of a running dog moves food through
the intestine rapidly, decreasing the times for digestion. Grinding foods is
helpful in increasing the digestive surface area, and has the positive effect of
increasing the speed of digestion.

Reproduction
Modern racing sled dogs are not free to roam and have no choices in mates.
The founding stocks (original) were dogs collected from populated areas in
the U.S. and Canada and, later, Siberia ( Coppinger, 1977 ). They tended to be
large pet and hunting/working breeds. They were trained to pull sleds. Dogs
that were not able to perform were destroyed. Often in the Canadian and
American gold rush periods, freight dogs were bought from ships, imported
at the beginning of winter and then destroyed at the end of the winter season
( Walden, 1928 ).
Humans chose from the remaining dogs, the better ones to be bred
together. Occasionally, new or different breeds are still introduced for a vari-
ety of reasons, such as increasing the variability and hybrid vigor. However,
mates are usually chosen from dogs that display the correct functional beha-
viors. Dogs showing particular conformation and behavioral

talents are

picked more frequently for breeding.

Hazard Avoidance
In order to successfully reproduce, sled dogs need to willingly pull the sled
continuously with other dogs. They therefore must not disrupt other dogs