The Cause of Hip Dysplasia
Hip Dysplasia. . . A dreaded term. . . Surgery. . .
Often, a death sentence for a loved one. . .
Have you ever noticed, when we veterinarians do not know
the answer, we will say, “It’s a virus,” or “It’s a pulled muscle,”
or “It’s genetic.” This is not a new phenomena. This has been going
on for years. Somewhere 40 to 50 years ago, a veterinarian noticed that
German Shepherds had a high incidence of hip dysplasia. He was seeing
it in very young pups. He was not seeing very much in other breeds,
and he was unable to find a cause. So he said, “It must be genetic.”
From that time on, it has been passed on to veterinary students as,
“Hip dysplasia is genetic.” So, don’t blame your Doc for tunnel vision.
It’s what we were taught.
Since hip dysplasia is now prominent in other breeds as
well, one questions how the genes causing hip dysplasia could have leaped
from one breed to another without crossbreeding. The cause obviously
is something other than genetic. I will agree that German Shepherds
are genetically predisposed to hip dysplasia, but the cause is a mechanical
problem, and it is seen in all breeds.
The cause of hip dysplasia is a dislocated sacrum. The
sacrum pinches spinal nerves (trunk lines of neurons). When the neurons
that enervate the muscles holding the hip ball and socket (head of the
femur and acetabulum) together are pinched, the neural impulse to the
muscles stops. The muscles become paralyzed and relax, allowing the
ball to drop or rotate out of its normal position - hip dysplasia.
The skeletal system is dynamic. It is always dissolving
and it is always recalcifying. The recalcification always forms along
the lines of force. As long as the lines of force have not changed,
the skeletal system remains normal. However, when the lines of force
have changed, as in hip dysplasia, the ball and socket remodels abnormally.
The acetabulum shallows, the head of the femur flattens, and the neck
of the femur thickens.
Once the sacrum is realigned into position, the neural
impulse returns to the muscles of the hip. They regain their tone (tension),
and pull the head of the femur back into its normal position. The ball
and socket begin remodeling back toward normal. The radiographs that
I have seen after realignment have shown no dysplasia of the hip, however,
those that were progressed, showed the neck of the femur still thickened.
It may be that it takes longer for that area to remodel, or there is
a point reached in the malformation, of no return?
The reason German Shepherds are predisposed to hip dysplasia
is two fold. They are a large breed with a narrow pelvis, and they have
long legs. When a pup passes through the birth canal, one shoulder squeezes
forward of the other shoulder, and one hip squeezes forward of the other
hip, making the pup narrower for the passage. In a large breed with
a narrow pelvis, or in any breed with an over sized pup, when the pressure
being applied forcing one hip forward is too much, the sacrum will dislocate.
Once the Shepherd has grown into their long legs, they
are then prone to dislocate the sacrum in another way. This usually
happens on a slippery surface, like linoleum, tile, wood floors, wet
cement, sealed cement, wet decks or wet grass. The dog will be running
and playing and make a sharp turn. The rear end slips out from under
them to one side, dislocating the sacrum. The longer the legs are, the
more leverage there is to cause this dislocation. The reason we are
seeing more hip dysplasia in other breeds than we did 40 to 50 years
ago is because dogs use to be kept outside, off of the slippery surfaces.
Now, they are house pets, slipping and sliding on surfaces design for
our comfort, not for their’s.
A less common way the sacrum is dislocated is when the
dog is tied down onto a surgery table for abdominal surgery. We are
taught first to anesthetize the dog, and place them on the table. With
the dog on its back, the front legs were then pulled up over their head
and tied down. Then one back leg was stretched and tied, and then the
other. The problem is when just one rear leg is being pulled down to
tie it down. It does not take very much force to dislocated the sacrum
in this manner due to the general anesthesia. The muscles have very
little tone.
What you can do to help prevent hip dysplasia:
Don’t play with the dog in the house if you have tile, linoleum,
or wood floors.
Place rubber backed throw rugs on slippery floors where the
dog normally makes a turn, or carpet all of your floors.
Don’t ever play frisbee with the dog.
Don’t play with you dog on wet grass.
If you throw balls or sticks for the dog to fetch, make sure
it is on the ground before the dog gets to it.
Paint your decks or cement runs with rubberized deck paint.
Cement must first acid etched. The deck paint can be found in Sail Boat
supply stores.
Selectively breed for a wider pelvis.
Good luck.
HOME