Siberian Husky: A breed of sled dog developed in northeastern Siberia and resembling the larger Alaskan malamutes.

Sickle Hocked: Inability to straighten the hock joint on the back reach of the hind leg.

Sickle Tail: A tail which is carried up and out in a semi-circle.

Sighthound: A hound that runs or courses game by sight rather than scent.

Silent Heat: An unnoticed heat period that can be due to little swelling of the vulva, little bleeding, no attraction of males or no behavior change.

Silky Coat: A topcoat composed of long, fine and soft hair.

Silky Terrier: A toy terrier of a breed developed from a cross between the Australian terrier and the Yorkshire terrier, characterized by long, silky, bluish-gray hair, tan markings, and erect ears.

Single Coat: A dog with only one type of coat, typically the topcoat or guard hairs, without the downy undercoat.

Single Tracking: All footprints falling on a single line of travel. When a dog breaks into a trot, his body is supported by only two legs at a time, which move as alternating diagonal pairs. To achieve balance, his legs angle inward toward a center line beneath his body, and the greater the speed, the closer they come to tracking on a single line.

Sire: The male parent.

Skeleton: Descriptively divided into axial (skull, vertebrae column, chest) and appendicular (forequarters, hindquarters) portions or the hard framework of the body; the bones of the body collectively.

Skull: The bony or cartilaginous framework of the head of vertebrates, made up of the bones of the braincase and face; cranium.

Skully: Thick and course through the skull.