Canine Hip Dysplasia
Hip dysplasia is a hereditary
disease that, in its more severe form, can eventually
cause crippling lameness and painful arthritis of
the joints. It is caused by a combination of genetic
and environmental factors. It can be found in many
animals and occasionally in humans, but is most
commonly associated with dogs, and is common in
many dog breeds, particularly the larger breeds.
Hip dysplasia is one of the
most studied veterinary conditions in dogs, and
the most common single cause of arthritis of the
Normal hip anatomy
In the normal anatomy of the hip joint, the femur
(the thigh bone) is connected to the pelvis at the
hip joint. The almost spherical end of the femur
head (the caput, or caput ossis femoris) fits into
the acetabulum (a concave socket located in the
pelvis). The bony surface of the femur head and
of the acetabulum are covered by cartilage. While
bones provide the strength necessary to support
body weight, cartilage ensures a smooth fit and
a wide range of motion. Normal hip function can
be affected by congenital conditions such as dysplasia,
discussed in this article, trauma, and by acquired
diseases such as osteoarthritis and rheumatoid arthritis.
Dysplastic hip anatomy
In a hip suffering from dysplasia, two things are
commonly abnormal. First, the caput is not deeply
and tightly held by the acetabulum. Instead of being
a snug fit, it is a loose fit, or a partial fit.
Secondly, the caput or acetabulum are not smooth
and round, but are misshapen, causing abnormal wear
and tear or friction within the joint as it moves.
The body reacts to this in
several ways. First, the joint itself is continually
repairing itself and laying down new cartilage.
However cartilage repair is a relatively slow process
(the most rapid bodily repairs are often in systems
with a blood flow, which cartilage lacks).
So the joint may suffer degradation
due to the abnormal wear and tear, or may not support
the body weight as intended. The joint becomes inflamed
and a cycle of cartilage damage, inflammation and
pain commences. This is a self-fueling process,
in that the more the joint becomes damaged, the
less able it is to resist further damage. The inflammation
causes further damage. The bones of the joint may
also develop osteoarthritis, visible on an X-ray
as small outcrops of bone, which further degrade
The underlying deformity of
the joint may get worse over time, or may remain
static. A dog may have good X-rays and yet be in
pain, or may have very poor X-rays and apparently
almost no problems. The hip condition is only one
factor to determine the extent to which dysplasia
is causing pain or affecting the quality of life.
In mild to moderate dysplasia it is often the secondary
effects of abnormal wear and tear or arthritis,
rather than dysplasia itself, which is the direct
causes of visible problems.
Causes and effects
In dogs, there is considerable evidence that genetics
plays a large role in the development of this defect.
There might be several contributing genetic factors,
including a femur that does not fit correctly into
the pelvic socket, or poorly developed muscles in
the pelvic area. Large and giant breeds are susceptible
to hip dysplasia, and Cocker spaniels and Shetland
sheepdogs are also known to suffer from it. Cats
are also known to have this condition, especially
To reduce pain, the animal
will typically reduce their movement of that hip.
In animals this may be visible as "bunny hopping",
where both legs move together, or less dynamic movement
(running, jumping), or stiffness. Since the hip
cannot move fully, the body compensates by adapting
its use of the spine, often causing spinal, stifle
(a dog's knee joint), or soft tissue problems to
In dogs, the problem almost
always appears by the time the dog is 18 months
old. The defect can be anywhere from mild to severely
crippling. It can cause severe osteoarthritis eventually.
It is most common in medium-large
pure bred dogs, such as German Shepherd Dogs, Labrador
or Golden retrievers, Rottweilers and Mastiffs,
but also occurs in some smaller breeds such as spaniels
and occasionally (usually with minor symptoms) in
Symptoms of Dysplasia
Dogs might exhibit signs of stiffness or soreness
after rising from rest, reluctance to exercise,
bunny-hopping or other abnormal gait (legs move
more together when running rather than swinging
alternately), lameness, pain, reluctance to stand
on rear legs, jump up, or climb stairs, subluxation
or dislocation of the hip joint, or wasting away
of the muscle mass in the hip area. Radiographs
(X-rays) often confirm the presence of hip dysplasia,
but radiographic features may not be present until
two years of age in some dogs. Moreover, many affected
dogs do not show clinical signs, but some dogs manifest
the problem before seven months of age, while others
do not show it until well into adulthood.
In part this is because the
underlying hip problem may be mild or severe, may
be worsening or stable, and the body may be more
or less able to keep the joint in repair well enough
to cope. Also, different animals have different
pain tolerances and different weights, and use their
bodies differently, so a light dog who only walks,
will have a different joint use than a more heavy
or very active dog. Some dogs will have a problem
early on, others may never have a real problem at
Each case must be treated on
its own merits, and a range of treatment options
The classic diagnostic technique is with appropriate
x-Rays and hip scoring tests. These should be done
at an appropriate age, and perhaps repeated at adulthood
- if done too young they will not show anything.
Since the condition is to a large degree inherited,
the hip scores of parents should be professionally
checked before buying a pup, and the hip scores
of dogs should be checked before relying upon them
for breeding. Despite the fact that the condition
is inherited, it can occasionally arise even to
animals with impeccable hip scored parents.
In diagnosing suspected dysplasia,
the x-ray to evaluate the internal state of the
joints, is usually combined with a study of the
animal and how it moves, to confirm whether its
quality of life is being affected. Evidence of lameness
or abnormal hip or spine use, difficulty or reduced
movement when running or navigating steps, are all
evidence of a problem. Both aspects have to be taken
into account since there can be serious pain with
little X-ray evidence.
It is also common to X-ray
the spine and legs, as well as the hips, where dysplasia
is suspected, since soft tissues can be affected
by the extra strain of a dysplastic hip, or there
may be other undetected factors such as neurological
issues (eg nerve damage) involved.
There are several standardized
systems for categorizing dysplasia, set out by respective
reputable bodies (Orthopedic Foundation for Animals/OFA,
PennHIP, British Veterinary Association/BVA). Some
of these tests require manipulation of the hip joint
into standard positions, in order to reveal their
condition on an X-ray, and since this is very painful
and must be held still for a clear image, often
the animal will be anaesthetized or sedated to achieve
clear diagnostic results.
Treatment of Hip Dysplasia in
There is no complete cure, although there are many
options to alleviate the clinical signs. The aim
of treatment is to enhance quality of life. Crucially,
this is a congenital condition and so will change
during the life of an animal, so any treatment is
subject to regular review or re-assessment if the
symptoms appear to get worse or anything significantly
If the problem is relatively
mild, then sometimes all that is needed to bring
the symptoms under control are suitable medications
to help the body deal better with inflammation,
pain and joint wear. In many cases this is all that
is needed for a long time.
If the problem cannot be controlled
with medications, then often surgery is considered.
There are traditionally two types of surgery - those
which reshape the joint to reduce pain or help movement,
and hip replacement for animals which completely
replaces the damaged hip with an artificial joint,
similar to human hip replacements.
Non surgical interventions
Non-surgical interventions include three elements:
weight control, exercise control, and medication.
Weight control is often "The single most important
thing that we can do to help a dog with arthritis",
and consequentially "reducing the dog's weight
is enough to control all of the symptoms of arthritis
in many dogs". Reasonable exercise stimulates
cartilage growth and reduces degeneration (though
excessive exercise can do harm too), and also regular
long walks in early or mild dysplasia can help prevent
loss of muscle mass to the hips. Medication can
reduce pain and discomfort, and also reduce damaging
Non surgical intervention is
usually via a suitable non-steroidal anti-inflammatory
drug ("NSAID") which doubles as anti-inflammatory
and painkiller. Typical NSAID's used for hip dysplasia
include carprofen and meloxicam (often sold as Rimadyl
and Metacam respectively), both used to treat arthritis
resulting from dysplasia, although other NSAIDs
such as tepoxalin (Zubrin) and prednoleucotropin
("PLT", a combination of cinchophen and
prednisolone) are also sometimes tried. NSAIDs vary
dramatically between species as to effect - a safe
NSAID in one species may be unsafe in another. It
is important to follow veterinary advice.
A glucosamine based nutritional
supplement may possibly be suggested to give the
body additional raw materials used in joint repair.
Glucosamine can take 3-4 weeks to start showing
its effects, since it can take up to 6 weeks to
reach full therapeutic effect in the body, so the
trial period for medication is usually around 3-5
weeks minimum before assuming it isn't working.
It's important to remember that glucosamine is not
a medication, it's a raw material, so the body still
takes considerable time to build more cartilage
once it has access to this raw material. Note that
the efficacy of glucosamine for such conditions
is uncertain; it is supported by some veterinary
sources, and considered unsupported by others.
It is also common, if necessary,
to try multiple anti-inflammatories over a further
4-6 week period. This is since an animal will often
respond to one type, but will fail to respond to
another. If one anti-inflammatory does not work,
a vet will often try one or two other brands for
2-3 weeks each, also in conjunction with ongoing
glucosamine, before necessarily concluding that
the condition does not seem responsive to medication.
Carprofen, and other anti-inflammatories
in general, whilst very safe for most animals, can
sometimes cause problems for some animals, and (in
a few rare cases) sudden death through liver toxicity.
This is most commonly discussed with carprofen but
may be equally relevant with other anti-inflammatories
too. As a result it is often recommended to have
monthly (or at least, twice-annually) blood tests
performed, to confirm that the animal is not reacting
badly to the medications, if these are being used.
Such side effects are rare but worth being aware
of, especially if long term use is anticipated.
(Main article: Rimadyl)
This regime can usually be
maintained long term, for as long as it is effective
in keeping the symptoms of dysplasia at bay.
If medications fail to maintain an adequate quality
of life, surgical options may need to be considered.
These may attempt to modify or repair the hip joint,
in order to allow pain free usage, or may in some
cases completely replace it.
Hip modification surgeries
include excision arthroplasty, in which the head
of the femur is removed and reshaped or replaced,
and pelvic rotation (also known as triple pelvic
osteotomy, or pubic symphodesis) in which the hip
socket is realigned, may be appropriate if done
early enough. These treatments can be very effective,
but as a rule tend to become less effective for
heavier animals - their ability to treat the problem
becomes reduced if the joint has to handle more
pressure in daily life. Pelvic rotation is also
not as effective if arthritis has developed to the
point of being visible on X-rays .
Femoral head ostectomy
(FHO), sometimes appropriate for smaller dogs and
cats, is when the head of the femur is removed but
not replaced. Instead, the resulting scar tissue
from the operation takes the place of the hip joint.
In such surgeries, the weight of the animal must
be kept down throughout its life in order to maintain
mobility. FHO surgery is sometimes done when other
methods have failed, but is also done initially
when the joint connection is particularly troublesome
or when arthritis is severe.
Hip modification surgeries
such as these usually result in reduction of hip
function in return for improved quality of life,
pain control, and a reduction in future risk.
Hip replacement is expensive
but (since it completely replaces the faulty joint)
has the highest percentage of success especially
in severe cases, usually restores complete mobility
if no other joint is affected, and also completely
prevents recurrence. Hip replacement for dogs, can
sometimes also be a preferred clinical option for
serious dysplasia in animals over about 40 - 60
lbs (20-30 kg), a weight that excludes certain other
surgical treatments. For additional information
and considerations for canine hip replacement and
other surgeries, see main article: Hip replacement
Overfeeding puppies and young dogs, particularly
in the giant breeds, might aggravate the problem
or bring it on earlier, because pups tend to be
more active, less aware of their physical limitations,
and have immature bones and supporting structures
carrying their weight. Dogs from
breeds which are known to be prone to dysplasia
can be kept slightly leaner than normal until around
2 years old, by which time the bones are full strength
and the animal can be easily brought up to its normal
adult weight. Over exercising young dogs, whose
bones and muscles have not yet fully developed,
might also be a contributing factor.
Responsible breeders who track
the incidence of hip dysplasia have been able to
reduce the incidence in some breeds but not to eliminate
There are many products on the market now to help
dogs suffering from hip dysplasia to get around.
These consist of pressure-reducing pet beds, ramps,
stairs, and steps built with wood, plastic, metal,
or foam that help the dog get from one place to
another without causing pain or hurting themselves