The canine skeletal system is a marvel of bones, cartilage, and ligaments that provide the body with a
framework to erect on four strong legs, protect internal organs, and provide a full range of motion. The
muscles furnish the power to propel the dog into action, but without healthy bones, joints, and connective
tissue, the muscles cannot do their job.
Joints — the skeletal hinges — give the skeleton flexibility for walking, trotting, running, jumping,
climbing, and moving the head and neck to increase the field of vision. The dog's body has three types of
joints: ball and socket such as the hip and shoulder joints; hinged joints such as the knees and elbows; and
gliding or plane joints such as the wrists and ankles. The joints are lubricated for smooth action by synovial
fluid and are stabilized by tendons and ligaments. When the joints are damaged by injury or disease,
arthritis (joint inflammation) can occur.
“He has arthritis” is probably the most common reaction of the pet owner whose Fido or Fluffy is stiff-
legged after exercise, has trouble getting up in the morning, or is reluctant to go up or down stairs. But
since such stiffness or lameness can have several causes and since arthritis itself comes in different types, a
trip to the veterinarian is a more prudent move than slipping the pooch a couple of aspirin for the
Degenerative joint disease
Arthritis results from inflammation in the joints and is generally divided into two types — degenerative
and inflammatory — according to the source of that irritation.
Degenerative joint disease (osteoarthritis) results from destruction of the cartilage that protects the bones
that make up the joint. Cartilage destruction can be the result of normal stress on abnormal joints or
abnormal stress on normal joints(1). Hip dysplasia(2), a malformation of the hip sockets, is one example of
normal stress on abnormal joints. Constant jumping over obstacles, stretching or tearing ligaments during
strenuous exercise, or i