YOUR DOG'S HEALTH
Hip Dysplasia
Genetic or Environmental
M.C. Wakeman, D.V.M.
BREEDERVET
One frequently encounters discussions which assert that hip dysplasia is 50% genetics and 50% environment. We prefer to think of it as 100% genetics, then 100% environment. Genetic considerations are the entirety of what we must as breeders consider. Once that puppy is born, environment is 100% of how well that puppy will do within the possibility of his genetics. Dogs with very good hips, congenitally, may have an injury and end up diagnosed as having 'unilateral hip dysplasia'. Individuals with very shallow sockets may be mobile and free of pain to an advanced age, if they have unlimited exercise. This is the entirety of what the owner of that puppy needs to concern himself with to provide the best possible care for his dog.
Over the years, our observations of the kennel populations of giant breeds and their siblings living in private homes have led to the conclusion that there is no such thing as congenital unilateral hip dysplasia, but only acquired unilateral hip dysplasia. The kennel dogs, whose exercise opportunities are maximized, with several dogs of a similar age free to run and play all day and night in large paddocks, show us some interesting things.
- They grow much more slowly, because much of their food intake goes into play and running.
- They rarely (almost never) suffer an injury.
- They always have symmetrical hip sockets, even if they are very shallow.
- They grow very large, very fast.
- They often suffer injury.
- They frequently have hip sockets of different depths.
The owners of giant breed pets tend to overfeed their puppies, having
with the best of intention, the inner desire to see a 'big dog' and to
do nothing which might risk the dog not attaining the greatest possible
size. Try as they may, some owners are just unable to restrict their
puppy's diet. Owners are cautioned that their puppy needs a good deal of
exercise, but their work schedules often conflict with their desire to
do this. The result is a period of intense exercise. A 3 mile run, or a
half hour of Frisbee. When a single puppy who lies around all day
welcomes his owners in the evening, he is ill prepared for either
intense exercise, or the uncertainty of footing on slippery floors and
his always changing joint angulation. His muscle tone is a small
fraction of that of a puppy which plays with other active dogs all day
long. The result is an injury.
When any dog has a hip dislocated, if it is not repaired within 48
hours, the socket begins to lose depth. When an injury occurs to a rear
leg, whether it be a toe injury, a stifle injury, a soft tissue injury,
or a hip injury, the result is often a decreased amount of weight
bearing on that leg over a period of days to weeks or months. When this
happens, the mechanical forces applied to the living bone tissue change,
and the hips become asymmetrical, the injured hip becoming shallower in
a similar fashion.
Many will find that a very controversial statement. Dr. Corley from
the OFA would reply to observations such as this, that he could prove
that unilateral hip dysplasia was genetic, since it was almost always
the left hip which was shallower. My response to his statement was that
this proves to me that most dogs are right handed. The left diagonal
being the master limb, the one with which the dog pushes off most
strongly, and the one which is most liable to injury, especially stifle
injury.
The conclusion from these observations is that the single most
important environmental factor in a puppy's life is exercise, continuous
and strenuous. Since this is often impossible for owners to arrange, the
next considerations are to drastically restrict the diet of the growing
puppy and to avoid strenuous exercise which will exhaust his muscles and
leave him unable to protect his joints from injury. The puppy should be
given frequent moderate exercise instead. This requires a different kind
of time commitment from the owner.
