This article is from the Canine Medical Information FAQ, by Cindy Tittle Moore with numerous contributions by others.
(from Corley & Keller)
"...[T]he signs [of hip dysplasia] vary from decreased exercise
tolerance to severe crippling. They include: a reluctance or inability
to go up or down stairs, difficulty in rising from a sitting or prone
position, bunny-hopping gait when running, stiffness early in the
morning that improves as the dog warms up, change in disposition due
to pain, lameness after exercise, wobbly gait, a clicking sound when
walking, and many others. Many dogs will shift their center of gravity
forward in an effort to relieve weight and pressure on the hips. These
dogs generally present a front end that appears well-developed
relative to the rear end.
"In dysplastic dogs, the hip joint is a weakened structure that is
more subject to being injured by normal activity such as jumping off a
couch, or rough housing with a playmate. Frequently, this results in
an acute lameness that in the mind of the owner was caused by the
injury, whereas the underlying dysplasia actually made the joint more
susceptible to injury. Obviously, the normal hip can be injured, but
the radiographic examination can usually distinguish between a hip
problem due to dysplasia and one due to other causes.
"CHD can not be diagnosed by observing how the dog moves, acts, lies
down, etc. The clinical signs may be caused by other problems;
therefore, a complete orthopedic and radiographic examination is
required before arriving at the conclusion that the signs are caused