Issue Description Hip dysplasia is an abnormal formation of the
hip socket that, in its more severe form, can eventually cause
crippling lameness and painful arthritis of the joints. It is a
polygenic trait, that is affected by enviromental factors in the
production of the final phenotype. 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. It is
one of the most studied veterinary conditions in dogs, and the most
common single cause of arthritis of the hips.
Overview Normal Hip AnatomyIn 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 AnatomyIn 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 tissue being avascular.
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 joint.
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, 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 Siamese.
To reduce pain, the animal will typically reduce its movement of that
hip. 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 arise.
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
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 cats.
Symptoms 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.
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 all.
Each case must be treated on its own merits, and a range of treatment
Diagnosis 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 categorising 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
anaesthetised or sedated to achieve clear diagnostic results.
Conditions which can mimic or replicate the
symptoms of hip dysplasia:
Cauda equina syndrome (i.e. lower back
Cranial (anterior) cruciate ligament tears
Other rear limb arthritic conditions
They add that: "Traditionally, the signs of hip dysplasia are rarely
extreme. Usually, only mild to moderate lameness is noted which may
suddenly worsen. Dogs with a cranial (anterior) cruciate ligament tear
typically hold the affected leg up (which is unusual with hip
dysplasia). Patients with back (spinal) problems often scuff their
toenails when walking, have an uncoordinated gait, and are weak in the
rear limbs. They may be very painful if they have a disc rupture
(sciatica) or show no spinal pain in certain degenerative spinal cord
conditions (German Shepherd myelopathy)." It is also worth noting that
a dog may misuse its rear legs, or adapt its gait, to compensate for
pain in the forelegs, notably arthritis, osteochondritis (OCD) or
shoulder or elbow dysplasia, as well as pain in the hocks and stifles
or spinal issues. It is important to rule out other joint and bodily
issues before concluding that only hip dysplasia is present. Even if
some hip dysplasia is present, it is possible for a painful case of
OCD or other diseases to be masked by mild dysplasia.
Long Term PainIt is important to note that a dysplastic
animal has probably lived with the condition since it was only a few
months old, and has therefore grown up taking the chronic pain for
granted and have learned to live with it. Dogs suffering such pain do
not usually cry out or show it. Sometimes, they will suddenly and
abnormally sit down when walking, or suddenly refuse to walk or climb
objects which they usually would, but this can equally be a symptom of
many other things, including a thorn in the paw, or a temporary muscle
pain. So pain recognition is less common a means of detection than the
visible gait and other abnormalities described above.
Treatment OverviewThere 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 changes.
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 InterventionsNon-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 inflammation.
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.
This regime can usually be maintained long term, for as long as it is
effective in keeping the symptoms of dysplasia at bay.
Other treatments such as class IV laser therapy have been found to be
remarkably successful in treating this joint problem/injury. The class
IV laser provides deep treatment of the joint using infrared coherent
Surgical InterventionsIf 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.
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.
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
Hip replacement (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.
Other options under exploration include:
DARthroplasty (Dorsal Acetabular Rim arthroplasty) is a technique
developed by Dr. Barclay Slocum and Theresa Devine Slocum whereby
cortico-cancellous bone strips, taken from the iliac crest, are
contoured over the femoral head and sutured to the dorsal hip joint
capsule and packed with additional cancellous bone graft dorsally to
eventually anchor to drill holes in the original dorsal acetabulum.
The new "shelf" eventually becomes an extension of the original
acetabulum, thereby providing support and eliminating subluxation of
the hip joint. The joint capsule becomes the new joint surface.
Pubic symphysiodesis (also known as juvenile pubic symphysiodesis, or
JPS), is a procedure for very young dogs that manipulates the way the
pelvis grows to create a tighter hip. It involves cauterizing the
growth plates of the pelvis, in other words, the part of the pelvis
which would usually grow and spread in puppyhood, no longer does so.
To compensate, the rest of the pelvis grows outward, in a manner which
enhances the "socket" of the hip and provides better support than that
dog would have had naturally. Since it relies on growth in puppyhood,
it has a very tight window for surgery -- currently no sooner than
about 4 months and no later than about 5 months. This is compatible
with hip scoring of puppies at 4 months.
Neurectomy, is a procedure in which the hip joint capsule is de-nerved
to reduce pain in the hip. This allows the dog to exercise moderately
with less pain, thus preventing the leg muscles from weakening from
disuse and providing less support to the bad joint. Both hips can be
done at one surgery. This surgery should not prevent a future hip
replacement, if a more complete fix is desired.
Additional HelpThere 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 further.