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Name
Hip Dysplasia, Canine
Short Description
Canine hip dysplasia
Affected Animals: Dogs. Less commonly, cats can develop hip
dysplasia, but the symptoms are much less threatening.
Overview: Difficult to prevent and treat, canine
hip dysplasia is among the most studied -- and the most frustrating
-- diseases in veterinary medicine. Canine hip dysplasia is a
developmental orthopedic disease in which an abnormal formation of
the hip leads to looseness in the hip joints, causing cartilage
damage. Progressive arthritis can result, and when it does, it can
be crippling. Hip dysplasia is not the same thing as arthritis in
the hips -- rather, it is the most common cause of arthritis in the
hips.
Some dogs will show clear signs of hip dysplasia at a very young
age, before the arthritis sets in. For them, a commonly used
surgical method is available to prevent its onset. But for many
canines, the symptoms will not be obvious until severe, crippling
arthritis has developed. At this point, the options for treatment
are limited and complex.
Because hip dysplasia is passed on genetically, there is perhaps an
even graver consequence of the disease remaining undiscovered: if
two dogs with undetected dysplasia are bred together, the painful
disease will be perpetuated in the gene pool.
Hip dysplasia is most common among larger breeds of dogs, especially
German shepherds, rotweillers, Labrador retrievers, golden
retrievers, mastiffs, and Saint Bernards. It can also be seen in
smaller breeds such as the cocker spaniel and the springer spaniel;
mixed breeds may suffer from it as well.
Clinical Signs: Decreased activity; difficulty rising; rear limb
lameness; reluctance to use stairs, particularly to go up;
reluctance to jump or stand on hind limbs; swaggering gait;
"bunny-hopping" gait; pain from manipulation of the hip(s);
decreased range-of-motion in the hips; crepitus in the hip joint;
positive Ortolani sign; positive Barden's maneuver; subluxation or
complete luxation.
Symptoms: Less energy and movement; difficulty rising;
lameness in the back legs; reluctance to use stairs (particularly to
go up); reluctance to jump or stand on hind limbs; swaggering gait,
"bunny-hopping" gait; soreness after lying down; soreness after
heavy exercise.
Description:
Canine hip dysplasia is a developmental
orthopedic disease. When a dog has dysplasia, it has an abnormal
development of the "ball-in-socket" joint that makes up the hip. In
a dysplastic hip, the "ball" (the head of the femur, or thighbone)
and the "socket" (the acetabulum, a portion of the pelvis), do not
fit together snugly. The result is a painful and damaging friction.
When a dog bears its weight on the joint, the friction strains the
joint capsule, which is a fibrous tissue that surrounds the joint
and produces joint fluid. The straining then damages the cartilage
and leads to the release of inflammatory proteins within the joint.
Thus begins the cycle of cartilage destruction, inflammation, and
pain -- the symptoms we associate with arthritis.
Among animals with hip dysplasia, the onset of
arthritis will vary. Some dogs will get it in early youth; for
others, it may not present itself until much later in life.
Frequently, two types of hip dysplasia are described: acute and
chronic. The acute (early) stage, usually seen in young dogs, is
characterized by intense pain in the hips and mild to severe
lameness. This stage can last from weeks to months. The chronic
(late) stage of hip dysplasia is characterized by pain, decreased
range-of-motion in the hips, and progressive arthritis. Chronic
dysplasia can develop in dogs less than one year old or it can take
many years to occur.
Hip dysplasia can result in a variety of clinical signs. Dogs can
have significant hip dysplasia and arthritis and show minimal or no
outward signs. Alternatively, hip dysplasia can -- and frequently
does -- result in crippling arthritis.
Hip dysplasia is most common among larger breeds, especially the
German shepherd, rottweiler, Labrador retriever, golden retriever,
mastiff, Saint Bernard, and others. It can also be seen in smaller
breeds such as the cocker spaniel and springer spaniel, as well as
in mixed breed dogs. Cats suffer from hip dysplasia, too, but their
symptoms are usually minor.
Diagnosis: The diagnosis is based on a physical examination
and x-rays. Currently, veterinarians have several different
techniques for taking x-rays of dogs with symptoms of hip dysplasia.
Recommended by the Orthopedic Foundation for Animals (OFA), the
hip-extended ventrodorsal view x-ray, which provides a frontal view
of the pelvis and hip joints, is most widely used and recognized by
veterinarians because the view best allows for an assessment of the
amount of arthritis present. To a lesser extent, this x-ray
technique also can evaluate how loose the hip joint is. The PennHIP
radiography technique is a much better judge of hip looseness,
however, and is actually used as an early detection test for hip
looseness in younger dogs. It can produce valid results in puppies
as young as four months of age. Other less commonly used methods of
diagnosing hip dysplasia include computed tomography (CT scan), and
ultrasonography.
Prognosis:
The prospect for recovery for non-surgical, or
"conservative," procedures is not clear-cut. It can be extremely
difficult to predict which animals will develop severe debilitating
arthritis, so it is always a risk to opt for conservative management
instead of surgery. Surgery, of course, carries its own risks.
The prognosis for dogs after a triple pelvic ostectomy is thought to
be very good if the operation is performed before the onset of
arthritis. When the arthritis has developed so that it is visible on
an x-ray, however, this type of surgery has a considerably reduced
chance for success.
As long as there are no complications, a total hip replacement is
very likely to result in a complete recovery from dysplasia.
Complications, however, could necessitate the removal of the
implants. The prognosis for femoral head ostectomy is generally good
for smaller dogs, and guarded for large or obese dogs.
Transmission or Cause:
Hip dysplasia is a legacy disease, passed through
the genes. Chances are that a loose-hipped dog that mates with
another loose-hipped dog will give birth to a dysplastic puppy. It
would seem, then, that the solution would be simple: to reduce the
incidence of the disease markedly, refrain from breeding two
dysplastic dogs. But the difficulty in preventing, as well as
treating, hip dysplasia is that not all dogs with hip dysplasia will
show signs of the disease. Thus, many seemingly normal dogs are bred
together, keeping hip dysplasia within in the gene pool.
Environmental factors also play a role in hip dysplasia. For
example, it is well known that obesity is a risk factor for the
development of arthritis. In addition, dog food that has been
over-supplemented with extra proteins, vitamins and minerals to make
puppies grow faster can create orthopedic problems in extremely
large breeds of dogs that may lead to hip dysplasia and arthritis.
Treatment: There are conservative, or non-surgical, methods for
treating hip dysplasia, such as pain medications, weight loss
programs, controlled exercise, and physical therapy. These methods
can be very effective in certain cases. However, conservative
treatments do have their limitations.
The other option is surgery. There are two
surgical approaches for dealing with hip dysplasia: prophylactic
procedures, which are designed to prevent the progression of
arthritis, and therapeutic procedures, which aim to treat or salvage
already arthritic hips. The primary prophylactic procedure available
is called a triple pelvic osteotomy. In this procedure, three
separate bone cuts are made in order to free the acetabular
component (the socket or cup) of the hip joint from the rest of the
pelvis. The acetabulum is then rotated to provide better coverage,
and a bone plate is applied to maintain this new position and allow
the bone cuts to heal. This procedure is quite effective if it is
performed before significant arthritis is present; after this time
period, it is no longer a useful procedure. A veterinarian can
assess whether the dog is a good candidate for this procedure.
Another type of preventative surgery, currently under clinical
investigation at several universities, is pubic symphysiodesis, a
procedure for very young dogs that manipulates the way the pelvis
grows to create a tighter hip. Studies are being conducted to help
determine whether this procedure is safe and effective. Aimed at treating hips that have already become
arthritic, the therapeutic procedures available for dysplastic dogs
include total hip replacement, femoral head ostectomy, and
investigational surgeries such as the DARthroplasty. In a total hip
replacement procedure, which is generally performed on a severely
debilitated dog weighing more than 50 pounds, a prosthetic hip
socket and a femoral head are implanted into the dog, forming an
artificial "ball-in-socket" joint. This gives the dog a pain-free
hip joint and nearly normal function after the recovery period.
Total hip replacement is a technically demanding surgery, and
usually is done by highly trained individuals at referral practices
and universities. When performed by experienced surgeons, the
success rate approaches 95 percent; nevertheless, complications,
while uncommon, can be devastating. For this reason, this procedure
is reserved for animals with the most severe signs of hip dysplasia.
Femoral head ostectomy is a surgery performed on severely arthritic
dogs. With this procedure, the femoral head ("ball" part of the
joint) is removed, allowing the femur to float about freely and
causing scar tissue to form. As the scar tissue hardens and
thickens, it serves to create a "false-joint" called a
pseudoarthrosis. The femoral head ostectomy is a last resort
procedure and generally is not recommended for mild cases of
arthritis. This procedure is more effective in smaller, well-muscled
dogs. Among dogs weighing more than 50 pounds, the results will
vary.
The DARthroplasty has been employed recently to
treat hip dysplasia in young dogs. With the goal of relieving pain,
this new surgical technique involves transplanting bone from the
pelvis to the hip socket in order to stabilize the joint. Since
controlled studies are lacking, and only a limited number of
surgeons can perform this procedure, the DARthroplasty should be
considered investigational until more information is gathered.
With any treatment, postoperative recovery depends not only on the
procedure, but also on the aftercare. The same principles of
non-surgical therapy are applied following surgery: obese animals
must lose weight and pain medications should be used when needed.
Follow the veterinarian's recommendations closely.
Prevention:
Conscientious breeding is vital to decrease the
occurrence of this devastating disease. Ideally, dysplastic dogs
should not be bred together to prevent the disease from staying in
the gene pool. However, it is not always easy to avoid breeding
dysplastic dogs, since it is so difficult to detect hip dysplasia in
dogs that do not show signs of arthritis.
Careful breeding is of course the best measure of prevention, but
for dogs born with the hip joint abnormality, the PennHIP x-ray
technique shows promise in allowing an earlier and more sensitive
detection of dysplasia.
A carefully planned diet is also a good measure of prevention.
Feeding large breed puppies over-supplemented, high-protein food in
order to force rapid growth has been shown to increase the incidence
and severity of arthritis in dysplastic dogs. Dogs fed a
calorie-limited diet will reach the same adult size as their overfed
counterparts -- more slowly, of course, but with a considerably
reduced likelihood of developing arthritis. Many pet food
manufacturers are recognizing this and are producing diets that are
tailored for large breed puppies. Consult with a veterinarian
regarding specific diets and feeding schedules to minimize the risk
of a dog developing arthritis from hip dysplasia.
Many veterinarians recommend x-rays of at-risk breeds at
approximately six months of age to screen for early evidence of hip
dysplasia, before the onset of arthritis. An ideal time to do this
is when the animal is presented for spaying or neutering because
then it will be already under general anesthesia, which usually is
necessary for taking appropriate x-rays of the hips.
Male and female dogs at risk for hip dysplasia that are intended for
breeding purposes should have their hips evaluated and certified by
the Orthopedic Foundation for Animals (OFA) at approximately two
years of age. A dog must be at least two years old before the OFA
will certify the hips.
