What is hip dysplasia?
Hip Dysplasia is a genetic disease due to an abnormally developed hip
joint. The cartilage that lines the joint is damaged which causes this
cartilage to loose it's ability to absorb the load that is placed on the
joint during movement. As the disease progresses there is inflammation
and the dog's body produces new bone at the edges of the joint
surface, joint capsule, ligament and muscle attachments.
The joint capsule also eventually thickens and the joint's range of
motion decreases.
No one can predict when or even if a dysplastic dog will start showing
signs of lameness due to pain. There are multiple environmental factors
such as caloric intake, level of exercise, and weather that can affect
the severity of lameness and radiographic changes. There is no rhyme or
reason to the severity of radiographic changes correlated with the
severity of lameness. There are a number of dysplastic dogs with severe
arthritis that run, jump, and play as if nothing is wrong and some dogs
with barely any arthritic radiographic changes that are severely lame.
Since HD is a chronic, progressive disease, the older the dog, the more
accurate the diagnosis of HD (or lack of HD).
We see veterinarians OVERREACT to a diagnosis of HD all too often,
frequently recommending expensive and invasive surgeries (Triple Pelvic Osteotomy,
Total Hip Arthroplasty or Pectineus Tendon Surgery to name a few) when most
cases can be easily managed with natural supplements that have no
side effects (MSM, Ester-C, Chondroitin, Glucosamine, Perna Mussel
etc.). If you bought your dog from a
reputable breeder and your dog is from good bloodlines with multiple
generations of cleared ancestry, the severity of the disease is
typically mild and is is rare that such extreme measures are needed to
manage the disease. It is much more common to see severe forms of the
disease in dogs purchased from back-yard breeders and puppy mills. If
your dog is diagnosed with HD - DON'T PANIC. Talk to your breeder or
someone that is knowledgeable and familiar with HD and various
management options before jumping into invasive or expensive treatments.
What are the various OFA grades, and what do they mean?
| Grades of Normal Hip Evaluations |
| Excellent - this classification is
assigned for superior conformation in comparison to other animals of
the same age and breed. There is a deep seated ball
which fits tightly into a well-formed socket with
minimal joint space. There is almost complete coverage of the socket
over the ball. |
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| Good - slightly less than superior but there
is a
well-formed congruent hip joint. The ball fits well
into the socket and good coverage is present. Statistically, most
Rottweilers with normal ratings will fall into this category. |
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| Fair - Assigned where minor irregularities in
the hip joint exist. The hip joint is wider due to the ball slightly
slipping out of the socket causing a minor degree of joint
incongruency. There may also be slight inward deviation of the
weight-bearing surface of the socket causing the socket to
appear slightly shallow. |
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| Borderline - there is no clear
cut consensus between the radiologists to place the hip into a given
category of normal or dysplastic. To increase the accuracy of a
correct diagnosis, OFA recommends taking additional x-rays at a
later date (usually 6 months). This allows the radiologist to
compare the initial film with the most recent film over a given time
period and assess for progressive arthritic changes that would be
expected if the dog is truly dysplastic. Most dogs with this grade
(over 50%) show no change in hip conformation over time and receive
a normal hip rating. |
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| Mild - there is
significant subluxation present where the ball is partially out of
the socket causing an incongruent increased joint space. The socket
is usually shallow only partially covering the ball. There are
usually no arthritic changes present with this classification and if
the dog is young (24 to 30 months of age), there is an option to
resubmit an radiograph when the dog is older so it can be
reevaluated a second time. Most dogs will remain dysplastic showing
progression of the disease with early arthritic changes. |
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| Moderate - there is
significant subluxation present where the ball is barely seated into
a shallow socket causing joint incongruency. There are secondary
arthritic bone changes along the femoral neck and head
(termed remodeling), acetabular rim changes and various degrees of
bone pattern changes called sclerosis. |
| Severe - there is significant subluxation present where the ball is partly or completely out of a
shallow socket. Like moderate HD, there are also large amounts of
secondary arthritic bone changes along the femoral neck and head,
acetabular rim changes and large amounts of abnormal bone pattern
changes. |
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Why isn't hip dysplasia eliminated by responsible breeders?
Unfortunately, most inherited traits, including inherited diseases, are
polygenic - which means that multiple genes are involved in the inheritance
of the trait and both the sire and dam must contribute one or more of
the genes that cause the trait to appear in the offspring. Because a
trait can skip generations it may appear to be erratic in it's
occurrence.
So if hip dysplasia can't be easily eliminated, why bother testing?
To date, no DNA tests have been developed to identify
the specific combination of mutant genes responsible for any polygenic
disorders. Therefore, we must rely on phenotypic evaluations (the external
expression of a trait) to make informed decisions regarding a dog's suitability for breeding
purposes. It is only through testing of individual
dogs for the presence of hip dysplasia and knowledge of the prevalence
of the hip dysplasia in bloodlines, related dogs and offspring that a
breeder can reduce the incidence or severity of the problem.
Examination of over 3700 dogs in Switzerland has proven that 42% of all
purebred dogs there are affected by HD despite control programs for the
last 30 years. Breeding with dysplastic dogs and lack of progeny control
are responsible for this slow progress. [M. Fluckiger, J. Lang, H.
Binder, et al. [The control of hip dysplasia in Switzerland. A
retrospect of the past 24 years]. Schweiz Arch Tierheilkd, 1995;243-50.]
Is it true that environmental factors can cause hip dysplasia?
Genetic hip dysplasia can not be caused by environment but environment
(diet, exercise, supplementation) can make hip dysplasia more or less evident
or problematic. While there are certainly other problems that can mimic
the symptoms of hip dysplasia (hip or pelvic injury, crutiate ligament
tear, panostiotis, normal arthritic changes due to age or excessive wear
and tear on a joint etc.) a
dog will not develop genetic hip dysplasia if it does not have the genes necessary
to produce the trait. There are countless ongoing HD studies that are
examining everything from the role of nutritional and environmental
factors to the time of year that a dog is born. Environmental factors
can definitely contribute to the age of onset of lameness and the
severity of changes or lameness. It is very clear from
the existing studies that there is a higher incidence of HD in
overweight dogs but more information is definitely needed to determine
if the obesity is the cause of the HD or if the obesity simply causes
the HD to become evident at an earlier age. Either way, overfeeding and
obesity definitely have a negative impact on HD. Click
here for an
excellent article on the role of environment on hip dysplasia by Dr. Mary C. Wakeman, D.V.M.
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