HIP DYSPLASIA
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 environmental 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.
Hip dysplasia is one of the most studied veterinary conditions in dogs, and the most common single cause of arthritis of the hips.
NORMAL HIP ANATOMY
In the normal anatomy of the hip joint, the root (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 tissue being avascular.
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 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.
A Labrador Retriever standing with hind legs close together to compensate for hip dysplasia.
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.
The causes of hip dysplasia are considered heritable, but new research conclusively suggests that environment can also play a role. To what degree the causality is genetic and what portion environmental is a topic of current debate. Environmental influences would include overweight condition, injury at a young age, overexertion on hip joint at a young age, ligament tear at a young age, repetitive motion on forming joint (i.e. jogging with puppy under the age of 1 year). As current studies progress, greater information will help provide procedures to effectively reduce the occurrence of this condition. My own condition has been proven to be genetical, via x-rays, tests etc.
In dogs, the problem almost always appears by the time the dog is 18 months old. Richard Pitcairn theorizes that the hips of young dogs are weakened by heavy vaccination.The defect can be anywhere from mild to severely crippling, and can eventually cause severe osteoarthritis.
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 pugs 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.
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 all.
Each case must be treated on its own merits, and a range of treatment options exist.
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 exhibit acute signs of pain. Sometimes, they will suddenly and abnormally sit down when walking, or 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.
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 (e.g. nerve damage) involved.
There are several standardized systems for categorising dysplasia, set out by respective reputable bodies.
TREATMENT
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 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
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 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. 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 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.
This regime can usually be maintained long term, for as long as it is effective in keeping the symptoms of dysplasia at bay.
SURGICAL TREATMENT
It is quite comforting to know that there are several types of surgery to treat the problem. Veterinarian surgeons can choose from different procedures to help canine patients. Usually, their choice is dependent on the severity of the dog’s condition and its age. Certain procedures can only be sustained by older dogs, while some are most effective when done on the younger dogs.
HIP REPLACEMENT:Canine hip dysplasia  is a degenerative disease. This means that it can get worse over time. If your dog is diagnosed to suffer degenerative hip dysplasia, it may have to undergo total hip replacement. This type of procedure aims to eliminate the pain and the degeneration of the hips.
The hip joints of the dog will be removed and prosthetics will be put in its place. When done successfully, the pain associated with this disease will be gone and the functions of the joints will greatly improve. However, only dogs weighing 20 pounds or more can undergo this procedure. Smaller and lighter dogs will not be cleared for it.
Aside from totally removing the hip bones, it is possible only the femoral neck and head to be removed to solve the problem. This is yet another surgical choice for vets. The procedure is usually done on pets that are not qualified for total hip replacement. While this procedure is mostly prescribed to lighter dogs, the larger breeds can also benefit from it.
TRIPLE PELVIC OSTEOTOMY: TPO, is one procedure effective for younger canines. If your pet is ten months old or less, this is the preferred surgery type. TPO is most effective for dogs that have severe laxity in the hips but have no observable damage in the joints. In the procedure, the pelvic bones are surgically broken down so that certain parts are realigned accordingly. While this type of surgery is very expensive, it is also one of the most successful procedures your dog can go through to correct the problem.
JUVENILE PUBIC SYMPHYSIODESIS: This is also a type of surgical procedure, although it isn’t as invasive. This surgery calls for the infusion of two hip bones. It is normally done to so that the problem joints will develop normally and correctly. The procedure is also known to lessen your dog’s risks of developing arthritis due to hip dysplasia.
Proper diagnosis is very important. By submitting your pet to regular check-ups, the vet will know the severity of the condition and devise the most effective way of correcting the problem. With all these surgical choices, the only way your pet can be treated accordingly is if you submit it to the necessary diagnostic exams.
I hope this has been helpful or at least of interest. Information from Wikipedia.
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