Definition of canine hip
dysplasia (CHD): a developmental defect initiated by the genetic predisposition
to the subluxation (dislocation) of a joint
The hip joint is a ball and
socket joint. The socket or acetabulum,
is situated within the pelvis, the ball or hip head, is located at the end of
the femur (thigh bone) in a normal hip joint, the ball fits closely and deeply
into the socket both (ball and socket) rotate smoothly, are cushioned by
cartilage and lubricated with a joint fluid (synovial). The better the fit of these parts, the less
wear the joint experiences, and the
longer it functions efficiently.
When the joint is loose,
this causes abnormal wear of the joint components; this wear can distort the
joint - leading to a degenerative joint disease (DJD) or arthritis. Hip
dysplasia is a condition of abnormal development of-or within the hip joint,
that results with joint instability (unsteadiness). The condition of developmental hip dysplasia can develop over the
first few weeks, months, or years of a dog's life.
It is not uncommon for elbow
dysplasia to occur with hip dysplasia; especially since dogs with hip dysplasia
may experience an altered gait. Elbow
and hip dysplasia can occur on one or both sides. The common symptom is a lameness that will shift the legs from a
natural position, and cause a swaying gait.
It is important to realize
that the underlying factor, or causes for dysplasia are genetic. The genetic predisposition (tendency) for
dysplasia causes the body react to certain diets, activities and environmental
factors, which in turn - enhances the dysplastic condition. Several genes interact (polygenetic) to produce
this condition, consequently making it difficult to isolate or eliminate that
one particular gene. Breeders who are
cautious about testing for the condition, help to decrease the occurrence by
controlling environmental factors: i.e. diets, exercise and selective breeding
pools. Outside factors which have been suggested as influencing the development
of dysplastic components are: overweight, extreme amounts of protein and energy
rich foods, rapid growth rates, excessive exercise, or lack of exercise, and
high calcium intakes. Studies have proven that mating only dogs with
radiographically normal hips have noticeably reduced dysplasia.
Elbows are also subject to
dysplasia and can be equally debilitating (incapacitating). Elbow dysplasia is a condition diagnosed
as: ununited anconeal process (UAP).
The elbow consists of three bones, the radius, and the ulna � which make
up the forearm (ulna, being the longer of the two bones) and the humerus or
upper arm, these three bones all fit together accurately to allow ease of movement. The upper end of the ulna (trochlea - a half moon shaped bone)
has attached tendons, which act as a pulley.
On the
Any dog, any breed, can develop this condition, dysplasia is not exclusive to just large
breeds. The occurrence of dysplasia can
be reduced through selective breeding practices, by selecting only animals that have disease-free radiographic
examinations, and clear family
histories of dysplasia free progeny.
Michele Scarberry, X-ray Technologist and GSD Breeder