HIP DYSPLASIA
What is hip dysplasia?
Hip dysplasia is defined as a deformity of the coxofemoral (hip) joint that
occurs during the growth period. Hip dysplasia is caused by a variety of factors
including genetic, overweight in the young puppy and over exercise, all of which
contribute to a poorly fitting hip joint. As the dog walks on this joint, arthritis
eventually develops, causing pain in the joint. The degree of lameness that
occurs is usually dependent upon the extent of arthritic changes in the hip
joint.
Is this found in certain breeds of dogs?
Most breeds of dogs can be affected with hip dysplasia although it is predominantly
seen in the larger breeds of dogs, such as the German Shepherd, St. Bernard,
Labrador Retriever, Old English Sheepdogs, etc. There is equal distribution
of the disease between male and female dogs.
What are the clinical signs, and when do they occur?
The typical clinical signs of hip dysplasia re weakness and pain in the hind
legs, lack of coordination, and a reluctance to rise. Wasting of the large muscle
groups in the hind legs may eventually develop. Most owners report that the
dog has had difficulty in rising from a lying position for a period of weeks
or months; lameness and pain subsequently develop. Again, the severity of signs
and progression of the disease usually correlate with the extent of arthritis
in the joint. Clinical signs can occur as early as 4-6 weeks of age, but most
dogs manifest the disease as a lameness around one to two years of age. Dogs
with mild hip dysplasia and minimal arthritis may not become painful and lame
until 6-10 years of age.
How is it diagnosed?
Tentative diagnosis of hip dysplasia is made on the basis of history, breed,
and clinical signs. A large breed dog that has been slow to rise for several
months and now is lame is a high suspect for hip dysplasia; a dog which refuses
to rise should also be considered a candidate. Because the clinical signs may
mimic other diseases, final diagnosis of hip dysplasia can only be made on the
basis of specific radiographic (x-ray) findings. To obtain the proper radiographs,
dogs must be carefully positioned on the radiographic table. This procedure
requires the use of a short-acting anesthetic or heavy sedation. The radiographs
are evaluated for abnormal shape of the hip joint and for degenerative changes
(arthritis).
How is it treated?
The degree of clinical signs and arthritic changes in the joints determine
the specific approach to therapy. Treatment of hip dysplasia may involve the
use of drugs or surgery, or both. The options are as follows:
l. Anti-inflammatory drugs: Several drugs will give relief from pain.
Non-steroidal anti-inflammatory drugs (NSAIDs) may work well in some dogs. In
others corticosteroids are used. Most drugs have some side-effects and therefore
the most suitable drug for your pet may require close cooperation between you
and your veterinary surgeon. Unfortunately, it is not possible to predict which
dog will respond to which drug. Therefore, a series of trials may be needed
to find the most effective one for your dog.
Extreme caution is advised when these drugs are given to dogs with a history
of kidney disease or with impaired kidney function. Many of these drugs have
an adverse effect on blood flow to the kidneys and can lead to kidney failure.
This does not appear to be a concern if kidney function is normal.
Anti-inflammatory drug therapy is most often used in older dogs, in dogs that
did not get good relief from surgery, or in dogs for which surgery is not feasible.
Both corticosterioids and NSAIDs may be contraindicated in dogs with a history
of gastric ulceration. However compromise may sometimes be reached by combining
the analgesic/anti-arthritic drug with an anti-ulcer compound.
2. Surgery: There are four main procedures: pectineal myotomy (muscle
cutting surgery), femoral head ostectomy (ball removal), triple osteotomy, and
total hip replacement.
Pectineal myotomy is a relatively minor procedure that involves cutting a
small muscle that puts pressure on the hip joint. It results in no loss of leg
function and gives good to excellent relief in 80-90% of dogs. If both hips
are abnormal, both hips may be operated at the same time. The dog recovers from
surgery in one to two days. However, this procedure does not stabilize the hip
joint or prevent progression of arthritic changes. Within a few months to several
years, pain and lameness will return.
Femoral head ostectomy (FHO) is another choice. The hip joint is a ball and
socket joint. FHO is the removal of the ball part of the joint. This gives excellent
results in small dogs because a functional "false joint" forms. However, some
large dogs may not form this "false joint" very well. This procedure is usually
used in large dogs if arthritis is very severe, if the hip dislocates, or if
the expense of the other procedures is prohibitive.
Triple osteotomy is a procedure in which the pelvis is cut in three places
around the hip joint. The bone is rotated to create better alignment with the
femoral head (the ball). It is reattached so that the joint functions in a more
normal fashion without looseness and pain. This should only be performed in
a dog with no arthritic changes in the joint. It is an expensive procedure.
Total Hip Replacement (THR) is possible, as is done in humans. The hip joint
is replaced with an artificial ball and socket often made of plastic and stainless
steel attached to the pelvis and femur in place of the abnormal joint. It is
another expensive procedure, but it may give many years of pain-free use of
the hips. Although the intent is for the transplant to be permanent, the new
joint may loosen after a period of time.
I am considering breeding my dog. Can anything be done to prevent hip dysplasia
in the puppies?
Research has shown that the cause of hip dysplasia is related to a combination
of genetic and environmental factors. The disease is known to be an inherited
condition and the genetics of hip dysplasia are extremely complicated. In addition,
environmental factors such as overfeeding and excessive exercise can predispose
a dog (especially growing puppies) to developing hip dysplasia. Because the
inheritance of the disease is so complicated, many questions remain regarding
eradication of the disease. Have your dog radiographed before breeding to be
sure the hips are normal. If they are not, this dog should not be bred.
Consider a feeding program to slow growth
There is a growing body of evidence indicating that dogs that grow very rapidly
are more likely to have hip dysplasia. Many authorities recommend feeding an
adult-type food to puppies of high risk breeds so their growth is slower. They
will still reach their full genetic body size, but just not as rapidly.
Avoid excessive exercise in a growing puppy. Any abnormality in the structure
of the hip joint is magnified if excessive running and jumping occur. It is
not necessary to treat your puppy as if it were handicapped, but long sessions
of running or chasing thrown objects can be detrimental to joints.
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