Lanebern Saint Bernards
WHAT IS HIP DYSPLASIA?
The hip is a ball and socket joint held together by a joint capsule, ligaments, and muscles. In order to function properly, and not to wear out prematurely, the ball (femoral head) and socket (acetabulum) must fit together with near perfect congruency. This is the situation in the normal dog. Hip dysplasia means abnormal growth of the hip joint. It is a developmental disease of dogs wherein laxity and incongruency develop between the femoral head and the acetabulum. Although hip dysplasia may be congenital (present at birth), in the dog it usually starts to develop in a progressive fashion at a few months of age. The disease is usually bilateral (both sides affected), although one side may be worse than the other.
If you are intending to breed from your dog or bitch, it is advised that you have your dog Hipscored under the relevant Scheme. In the UK this is the KC BVA scheme. The 'ideal' age is just after the dog turns 12months of age. It has been said that in bitches, they are x-rayed 2-3 months after their season (or heat), but again after 12months of age. The X-ray MUST be done by a registered Veterinary practise.
WHAT CAUSES HIP DYSPLASIA?
The exact cause(s) in dogs is unknown. Although many factors have been implicated, Environmental factors also may play a role in the development of hip dysplasia. Hip dysplasia (and other orthopaedic abnormalities in young growing dogs) is often associated with diets supplemented with extra protein, calcium, and calories. Rapidly growing puppies tend to be the most severely affected. The common thread appears to be genetic predisposition. Hip dysplasia is seen in all breeds of dog, and often runs in family lines. Multiple genes are involved, and not all dogs who carry these genes develop hip dysplasia themselves, nor are all dogs who have hip dysplasia accurately diagnosed by examination or radiographs (x-rays). Hence, it is common to have puppies with hip dysplasia, even severe cases, to come from bloodlines where hip dysplasia has not been observed previously. .
HOW CAN I TELL IF MY DOG IS DYSPLASTIC?
The presence of hip dysplasia does not always result in clinical signs that are appreciated by the owner, or even the veterinarian. Hence, some dysplastic dogs are never diagnosed, or else are diagnosed only after significant derangement of the hip joints has occurred. Although some veterinarians claim to be able to recognize the disease in puppies as young as 6 weeks, most puppies do not develop the disease or show signs until about 4 months of age. In some cases, and with some methods of detection, it may take as long as two years before hip dysplasia is evident; the discrepancy probably relates to individual variation in how quickly the disease develops. Typical signs seen by owners of dogs developing hip dysplasia are those of mechanical lameness. Because of the poor fit between the ball and socket, affected animals will often have abnormal gaits, including a sashaying rear end, tendency to bunny hop (run with both legs together), slowness/awkwardness in sitting or rising, and possibly earlier-than-expected fatigue after exercise. Occasionally owners will report hearing a popping or clicking noise when the dog moves; this is the result of the femoral head moving into and out of the acetabulum. Sometimes the owner may be unaware there is a problem until the dog is taken to obedience school, where an astute and experienced trainer may notice the dog being reluctant to sit squarely. In the early stages of the disease, pain is NOT a common finding, and treatment with analgesics (such as aspirin) does not seem to help.
Since clinical signs may be absent, especially early on in the course of the dysplastic process, it is important for animals suspected to be at risk because of their breed to be evaluated EARLY by their veterinarian. As alluded to above, this includes puppies from guaranteed hip dysplasia-free bloodlines. Such evaluation should include both an awake orthopaedic examination, and one done under heavy sedation or general anesthesia. The latter allows for complete muscle relaxation and critical assessment of hip stability. In addition, x-rays can be taken which assists the doctor in uncovering any dysplastic tendencies. The earlier the diagnosis is made, the more options are still available, including attempted correction or starting over with a new puppy. If using the Orthopedic Foundation for Animals (OFA) standards for detecting hip dysplasia remember that the absence of clinical, examination or radiographic signs of hip dysplasia before two years of age does NOT guarantee that dysplasia wont still show up later; thus, and animal at risk should be evaluated on a regular basis until reaching two years of age, and immediately if any of the clinical signs described above are noticed. Conversely, dogs with hip dysplasia do not outgrow their disease; hence, although a dog cannot be certified as free of hip dysplasia until reaching two years of age, once the diagnosis is made (no matter how early), the dog should receive appropriate hip dysplasia management.
There are several x-ray methods of diagnosing hip dysplasia. These are constantly being refined and new ones added to try any improve the accuracy of diagnosis. The two most widely used are the OFA (Orthopedic Foundation for Animals) and PennHip examinations. The latter has many advantages, but also requires that the veterinarian performing the exam be certified. Therefore, not every veterinarian can do the PennHip test. The PennHip exam also requires more time and radiographs (x-rays), so tends to be more expensive than the OFA exam. Part of the PennHip exam includes an OFA-type evaluation as well, but it is not sent to the official OFA site. OFA has been around many years more than PennHip and for that reason alone has been seen as the standard in the breeding and veterinary professions. However, PennHip provides more reliable and quantifiable measurements of hip dysplasia, and can be used with greater reliance for prognosis.
WHAT ARE THE IMPLICATIONS OF HIP DYSPLASIA?
First, dogs with hip dysplasia are probably carrying a genetic load which is likely to be passed on to offspring in the next or subsequent generations. Since this can be such a disabling disease (and an expensive one to manage!), we should strive, through careful breeding, to keep all known carriers out of the breeding population. Affected animals should not be bred, and consideration should be given to spaying (removing the ovaries) female dogs, and castrating male dogs. Obviously such dogs are generally unsuitable as show dogs, since the goal behind showing most dogs is to establish the particular animal as a quality-breeding animal. Breeders of affected animals should be notified, as should owners of siblings and other close relatives.
Because hip dysplasia implies incongruency between femoral head and acetabulum, there is constant and repetitive abnormal stress on affected joints. Joint surfaces are composed of hyaline cartilage which covers the underlying bony surface. With the abnormal biomechanical forces present over time, this cartilage starts to undergo wear and tear changes. Since hyaline cartilage is not replaced by the body, such degenerative changes are permanent and irreversible. As the ball moves in and out of the socket, there is also wearing away of the top of the acetabulum, called the dorsal acetabulum rim. This leads to a vicious cycle, since, as the rim is worn away, the effective depth of the socket is decreased, and the ball becomes more and more sublaxated (dislocated) from the acetabulum. In an effort to counteract the instability, Mother Nature tries to hold things together by thickening the ligaments and joint capsule which normally hold the ball and socket in close apposition. Often this is accompanied by the development of bony spurs, called osteophytes, along the attachment sites if the joint capsule on the femoral head and neck, and on the acetabulum. This entire process of cartilage wear and tear, instability, soft tissue thickening, and osteophyte development is termed degenerative joint disease or osteoarthritis. Thus, the natural progression of hip dysplasia over time is toward the development of arthritis in the affected joint(s). Once arthritis develops, it is indistinguishable from the arthritis seen in elderly patients after a lifetime of wearing out their (normal) hips. The onset of arthritis in dogs with hip dysplasia is variable; some dogs may already have arthritic changes by 6 or 7 months of age, while in others it can take several years to develop.
Needless to say, arthritis may cause substantial limitations in normal activity for an affected patient, including severe pain. Thus, dogs with hip dysplasia not only face problems owing to the instability in the hips during the early phases, but are likely to develop even worse disability and discomfort as the disease progresses.
WHAT DO I DO IF MY DOG IS DIAGNOSED WITH HIP DYSPLASIA?
There is no universal answer applicable to every dog. Such factors as age, stage of disease, severity of dysplasia, intended use of the dog, and the presence of concomitant orthopaedic problems are among the considerations which must be weighed in formulating a management plan. Not all dogs with hip dysplasia require treatment. Even though dysplastic dogs are likely to go on to develop arthritis, this does not automatically mean that such dogs will develop CLINICAL lameness or pain. Treatment is always predominantly based on the animal, and not on what is felt by the veterinarian or seen in the radiographs. Similarly, young dogs with hip dysplasia do not always have mechanical lameness. Thus, a great deal of judgment is required, and ongoing reevaluation of the plan is necessary in order to deal with changing conditions over time.
In young dogs who are experiencing mechanical lameness, not pain, there is little that can be done with medication or other conservative measures to substantially change the dogs clinical function. To whatever degree diet may play a role in exacerbating the severity of the hip dysplasia, it might be helpful to ensure that the dog (even if still a puppy) is on regular, adult dog food, without supplementation, or specifically formulated large breed growth diet. Although this will not undo the dysplasia, it may help limit the progression. For young dogs who are having clinical signs of pain (limping, elevating a limb off the ground, crying, soreness after exercise, etc.), a careful examination must be performed by the veterinarian to differentiate whether the pain is due to the hips, or to some other cause. It is not uncommon for dogs afflicted with hip dysplasia to also develop other orthopaedic diseases, such as panosteitis (an inflammatory condition of the bones). And for the hip dysplasia to be a red herring. Treatment for such patients requires attention to the immediate cause of discomfort, and formulation of a plan to treat or follow the hip dysplasia.
Dogs who are experiencing pain and disability due to their hip dysplasia usually are arthritic. Occasionally, young dogs without arthritic changes in their hips will have pain owing to a sprain type injury to the hip(s), where the joint capsule is stretched or partially torn. Medical treatment for dogs with painful hips should always be attempted before turning towards surgical solutions. Many animals can avoid, or long-postpone the need for surgery using a variety of less costly therapies.
Common sense dictates that the smaller the patient, and the less load the hips have to handle, the less likely the stress of weight-bearing is going to cause pain. Owners of dogs with arthritic hips should work with their veterinarian in getting their pets on appropriate types and amounts of food to ensure a lean physique.
Neither too much nor too little activity is good for arthritis. Prolonged periods of inactivity lead to joint stiffness and soreness when rising. Heavy exertion causes increased wear in the joints, and results in substantial pain minutes to hours after exercise. The best solution is to provide regular but moderate amounts of exercise each day. This means that dysplastic/arthritic dogs should not be allowed to be sedentary all week, and then be asked to run, jump, swim, play to the maximum on the weekend. As a general rule, swimming is therapeutic exercise, since it allows for movement of the joints and use of muscles without high impact; unfortunately, most dogs do not quietly swim laps, but rather bound in and out of the water along the edge, so that the beneficial effects of swimming may be negated. Formal physical therapy can also be employed to preserve as much pain-free and athletic function as possible.
A variety of medications are available to modify the animals response to pain, and many animals can be managed well enough with medications to avoid the need for surgery. The most commonly used medications are termed non-steroidal anti-inflammatory drugs, or NSAIDs. This broad category of drugs includes such familiar products as aspirin, acetaminophen (Tylenol), and ibuprofen (Motrin, Advil, Nuprin), and others available over-the counter or by prescription. It is important to use such medications only on the advice of your veterinarian, and with careful attention to dosage, frequency, and observation for side effects. Some drugs, which are safe in humans, can be quite toxic in animals, causing everything from acute gastritis, to bleeding ulcers, to more severe complications as bone marrow, kidney, or liver poisoning. Nowadays we are fortunate to have a host of canine-specific NSAIDs that are generally safer and more effective than trying to use any human products. Corticosteroids (Cortisone) are also used in some patients for their anti-inflammatory properties. These drugs can be given orally, by injection, or placed directly on the joint. While often highly effective, there are many potential complications associated with prolonged use, and so the use of steroids is usually limited to short time spans. Narcotic and narcotic-like analgesic agents are rarely employed for arthritis, since they are relatively ineffective in controlling musculoskeletal pain. The most recent fad for medical treatment of hip dysplasia, and particularly the ensuing arthritis, is the use of so-called chondro (cartilage) protectant agents. The oral forms, of which there are many formulations, are being touted as neutraceuticals, a term coined to convey the idea that nutritional supplements are effective in a way similar to approved drugs. Because of their status as food additives, they are not subject to government oversight of safety and efficacy. The most common constituents of these products are chondroitin sulfate and glucosamine. Other commonly used supplements are shark cartilage, vitamins, and other herbal products of dubious value. Over time, some of these products may be shown via scientific (i.e., controlled, double-blind) studies to be efficacious. However, consumers (YOU), and doctors should maintain a vigorous and vigilant level of skepticism when confronted with clams based entirely on unfounded or anecdotal evidence. Finally, although not a drug in the conventional sense, acupuncture has gained acceptance as a sometimes-useful treatment for a variety of painful musculoskeletal conditions. A veterinarian who has been specially instructed on the appropriate use of the technique can offer these treatments.
Two cautions are in order for those seeking non-surgical management options for their arthritic pet. One concerns the use of non-standard drugs and treatments such as holistic healing, usually based on various herbs, vitamins, dietary changes, etc. Just as with people, arthritis is a persistent and difficult to control disease in animals. Unfortunately, the absence of a scientific cure leaves the field wide open for opportunistic individuals to market a variety of miracle cures. While it is inappropriate for the scientific community to mock all non-traditional treatments, the pet owner, as consumer and guardian, must take care to distinguish between innocuous, well intentioned treatments, and potentially harmful products hawked by the modern day equivalent of the snake-oil salesman. The second, and related caution is in regards to the potential use of chiropractic in dogs. Chiropractic manipulation of people is a time-honored, although poorly-understood method of relieving musculoskeletal discomfort. That it often succeeds in cases where physicians have been otherwise stymied suggests that, even in the absence if a good explanation why, chiropractic does play some role in management of some disorders. A chiropractor may not treat an animal for money unless under the direct supervision of a licensed veterinarian. A few veterinary professionals have dual training in chiropractic and these are the only individuals who should be trusted in applying this treatment modality to dogs.
Surgical treatment for hip dysplasia can be broadly broken down into two classes, either surgery which attempts to correct hip dysplasia, or so-called salvage surgeries which seek to provide long-term relief from pain. Candidates for the first type of surgery are generally immature dogs (less than 12 months old), who have clinical disability due to mechanical instability, and who have not yet developed significant wearing or arthritis of their hips. Corrective surgeries for this class of patients all share the common goal of undoing the incongruency and instability between the femoral head and the acetabulum. This entails either moving the ball closer to the socket, or the socket closer to the ball, or both. Operations that can accomplish these goals include triple pelvic osteotomy (moves the acetabulum), intertrochanteric varusizing osteotomy of the femur, and femoral neck lengthening (the latter two alter the position of the femoral head). The appropriate selection is made after review of all factors, including physical examination, orthopaedic examination, radiographs (x-rays), intended use of dog, and owner concerns and observations. When successful, these operations result in the undoing of the hip dysplasia, and allow normal weight-bearing, mechanical function, and wear of the hips, thus preventing the later development of disabling arthritis. Because the success of these operations is dependent on intervening before damage is too severe, it is imperative that surgery be performed promptly after the diagnosis has been made, and the dog determined to be a suitable candidate.
Another method of accomplishing the undoing of hip dysplasia (ie, moving the ball and socket together and keeping them snug) is to intervene while puppies are still very young with an operation called juvenile pubic symphysiodesis (sim-fizi-o-dee-sis) (JPS). In this procedure (often done in conjunction with elective neutering) electrocautery is used to prematurely close the growth plate that forms the floor of the pelvis. When done at a young enough age (generally the best results are seen when done before the puppy is 16 weeks of age, and there is virtually no benefit after 20 weeks of age), the closure of this growth plate results in more outward growth of the part of the pelvis containing the acetabulum, and thus results in an improved congruency of the ball and socket. It accomplishes much the same goal as the operations described above without the trauma of major surgery. But it has to be done at 3-4 months of age to be effective.
When the hip dysplasia is so severe that the femoral head and acetabulum cannot be reduced to a normal relationship, or arthritis has already become established, the efficacy of corrective-type surgeries drops off precipitously. When such an animal is experiencing pain that interferes with normal daily function, and conservative medical therapies have failed, a salvage-type surgery may be indicated. The term salvage operation is chosen because it implies the final step in management, and because it can be done at any point in the patients life (with a few exceptions) rather than being critical early on. Currently there are two major operations classified as salvage operations for canine hip dysplasia/osteoarthritis: Femoral head and neck excision arthroplasty (also referred to as femoral head ostectomy) is an operation wherein the head and neck of the femur are removed. The space between the remainder of the femur and acetabulum is eventually filled with scar tissue, forming a false joint or pseudoarthrosis. The goal of this procedure is to eliminate the grinding of bone on bone, and thus afford pain-relief. It is a relatively simple surgery requiring a minimum of postoperative care, and entails modest cost. Its main drawback is that normal mechanical function is sacrificed, and the animal may still have substantial limitations in athletic ability; The premier choice for salvage operation is total hip replacement. This operation involves the removal of the arthritic ball and sockets, and replacement with man-made joint components. Its drawbacks are expense, need for careful management for the first few postoperative months, and the potential for complications such as dislocation, loosening, or infection. However, these potential complications are far outweighed by the advantages, which include normal, pain-free, mechanically sound hip function, even in very athletic dogs.
Other operations can be used as stop-gaps, temporary treatments, or surgical band-aids at various stages of the disease. When confronted with a young dog that is no longer a good candidate for corrective surgery, but is yet too young for hip replacement, and the puppy is very uncomfortable, it may be helped with an operation called pectineal myotomy. This is an old operation where one of the tight groin muscles that lies just under the hip is cut. It can provide some temporary relief from pain, although it does nothing to alter the course of hip dysplasia otherwise. It can be done bilaterally and does not preclude the later use of hip replacement. For older dogs where medication is insufficient for pain control but hip replacement or femoral head and neck excision are not currently options, an operation can be done to denervate the hip joint capsule. This may provide pain relief for several weeks to several months.
The information in this paget has been designed to provide a comprehensive, but brief overview of the many factors involved in the discussion of canine hip dysplasia. The status of your animal, and the need for any diagnostic or therapeutic intervention, can only be determined by careful and individual evaluation by your veterinarian or other consultation with a board-certified veterinary orthopaedic surgeon