Canine hip dysplasia
Hip dysplasia, Hip arthritis
Overview:
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.
Difficult to prevent and treat, canine hip dysplasia is among the most studied and the most frustrating diseases in veterinary medicine. 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.
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.
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.
symptoms:
Dogs of all ages are subject to hip dysplasia and the resultant osteoarthritis. In severe cases, puppies as young as five months will begin to show pain and discomfort during and after exercise. The condition will worsen until even normal daily activities are painful. Without intervention, these dogs may eventually be unable to walk. In most cases, however, the symptoms do not begin to show until the middle or later years in the dog's life.
The symptoms are similar to those seen with other causes of arthritis in the hip. Dogs often walk or run with an altered gait. They may resist movements that require full extension or flexion of the rear legs. Many times, they run with a 'bunny hopping' gait. They will show stiffness and pain in the rear legs after exercise or first thing in the morning. They may also have difficulty climbing stairs. In milder cases dogs will warm-up out of the stiffness with movement and exercise. Some dogs will limp and many will become less willing to participate in normal daily activities. Many owners attribute the changes to normal aging but after treatment is initiated, they are surprised to see a more normal and pain-free gait return. As the condition progresses, most dogs will lose muscle tone and may even need assistance in getting up.
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.
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.
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 several surgical procedures available to treat hip dysplasia depending on the dog's age, body size, and the severity of the hip joint's degeneration.
Triple Pelvic Osteotomy (TPO): TPO is a procedure used in young dogs usually less than 10 months of age that have radiographs that show severe hip laxity, but have not developed damage to the joints. The procedure involves surgically breaking the pelvic bones and realigning the femoral head and acetabulum restoring the weight-bearing surface area and correcting femoral head subluxation. This is a major surgery and is expensive, but the surgery has been very successful on animals that meet the requirements.
Juvenile Pubic Symphysiodesis: A less invasive surgery for treating hip dysplasia is called Juvenile Pubic Symphysiodesis. This surgery prematurely fuses two pelvic bones together, allowing the other pelvic bones to develop normally. This changes the angle of the hips and improves the articulation of this joint, lessening the likelihood of osteoarthritis. Early diagnosis is critical, since the procedure must be done before 20 weeks of age, preferably 16 weeks, and before any signs of arthritis are evident.
Total Hip Replacement: This may be the best surgical option for dogs that have degenerative joint disease as a result of chronic hip dysplasia. Total hip replacement is a procedure that can produce a functionally normal joint, eliminate degenerative changes, and alleviate joint pain. The procedure involves the removal of the existing joint and replacing it with an artificial joint or prosthesis. To be a candidate for this procedure, the animal must be skeletally mature. With the new micro-prosthetics there is no minimum size limit. In addition, there is no maximum size limit. If both hips need to be replaced, there is a three-month period of rest recommended between the surgeries. As with the TPO surgery, this is an expensive procedure but it produces very good results. Most dogs return to a near normal level of activity without pain.
Femoral Head and Neck Excision: Femoral head and neck excision is a procedure in which the head of the femur is surgically removed and a fibrous pseudo-joint replaces the hip. This procedure is considered a salvage procedure and is used in cases where degenerative joint disease has occurred and total hip replacement is not feasible or if the expense of a total hip replacement is prohibitive. The resulting pseudo-joint will, in most cases, be free from pain and allow the animal to increase his activity, however, full range of motion and joint stability are decreased. For best results, the patient should weigh less than 40 pounds; however, the procedure may be performed on larger dogs.
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.
There are many different theories on how to prevent the progression of hip dysplasia. As discussed earlier, poor nutrition, inadequate or improper exercise, and increased body weight may all contribute to the severity of osteoarthritis after the hip dysplasia has developed. Following solid recommendations for exercise and nutrition may help, but will never come close to controlling or eliminating the disease if stricter requirements for certified hips are not instituted or demanded.
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