Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

THE
C h a p t e r
MUSCULOSKELETAL
SYSTEM
The dog’s skeleton is made up of 319 bones—about 100 more than humans
have. Although the number of bones is roughly the same in all breeds, there is
considerable variation in the size and shape of individual bones, as the result
of selective breeding.
The place where two bones meet is called a joint, or articulation. In some
joints there is a cushioning pad of cartilage interposed between the bones.
This pad is called a meniscus. A damaged meniscus can deteriorate and
inflame the joint. Abnormal wear and tear on joint surfaces and joint cartilages
leads to arthritis. In many cases the abnormal wear and tear is the result
of poor joint conformation associated with inherited orthopedic abnormalities
such as hip dysplasia.
Joint position is maintained by the ligaments, the tendons, and a tough
fibrous capsule surrounding the joint. Together, these structures provide stability
and hold the joint together. Joint looseness (called laxity) is caused by
stretching of these support structures. Laxity enables the ends of the bones to
slip partly out of position. When the joint capsule ruptures, the bones slip
completely out of position. This is called dislocation.
The skeletal anatomy of humans and dogs has much in common, including
similar terminology. However, there are significant differences in the angles,
lengths, and position of the bones. The dog’s hock, for example, is actually the
heel bone in humans. While people walk on the soles of their feet, dogs walk
on their toes. Humans carry all their weight on their hips. Dogs carry 75 percent
of their weight on their shoulders and front legs.
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