Canine hip dysplasia (CHD) is one of the most prevalent orthopedic abnormalities that is seen in dogs today. Affecting millions of canines, it causes significant weakness and pain in many of those afflicted with it. By definition it is the abnormal or disordered developmental formation of the hip joint. Hip dysplasia was first recognized and described in veterinary literature in 1937.
In order to properly discuss hip dysplasia, it is important to have a basic understanding of the hip joint anatomy. It is essentially a ball and socket joint. The head of the femur being the ball and the acetabulum of the pelvis the socket. Synovial (or joint) fluid and the joint capsule, in addition to the surrounding musculature, contribute to the stability of the joint.
The abnormal formation or laxity (looseness) of the hip joint causes an abnormal weight bearing on the cartilage surfaces within the joint. This in turn leads to degenerative joint disease (DJD) or osteoarthritis. CHD is a heritable abnormality and affected by multiple environmental factors although the clinical signs are not present at birth.
Two age groups of dogs are primarily effected. Young dogs 4 – 12 months and adult dogs over 15 months of age are most frequently diagnosed. It predominantly is seen in large breed dogs, but has been seen in all breeds and even cats. The clinical signs may have a slow and gradual or a very sudden onset. Afflicted dogs will typically have an abnormal gait that can be described as “bunny hopping” on the rear limbs. The dog will have increasing difficulty rising and a decreased willingness to walk, run or climb stairs. Muscle atrophy or thinness of the hind limbs is often noted and sometimes an audible “click” will be noted as the hip partially pops out of joint with each step. I have personally seen some dogs initially present with a front limb lameness, only to have hip dysplasia diagnosed. This is due to the patient shifting more weight to the front legs in order to lessen stress on the hips. The resulting excessive wear and tear causes the front leg lameness.
A common misconception is that there is little an owner can do, while there are actually many treatment options for dogs with CHD. Medical (conservative) and viable surgical options do exist. I strongly believe that the medical options need to be multifaceted to be effective.
Non-steroidal antiinflammatories (NSAIDs) that are most often used include Rimadyl (carprofen) and Etogesic (etodolac). These medications decrease inflammation and the resulting pain associated with hip dysplasia. The two noted above are very potent and overall very safe NSAIDs. Potential side effects in a small percentage of patients include vomiting, diarrhea and liver toxicity. Most dogs receive these medications daily with little or no problems, but monitoring of certain blood values every 4-6 months is required. Human equivalent NSAIDs include aspirin and ibuprofen. Aspirin has actually been shown to worsen arthritis when used chronically and ibuprofen can be intensely irritating to a dogs stomach.
Polysulfated glycosaminoglycans (PGAs) are cartilage-protective agents that increase the quality of the joint and hopefully delay the progression of degenerative joint disease. While they are not direct analgesics (pain killers), I firmly believe based on my clinical experience that they often indirectly decrease pain associated with degenerative joint disease. They are very safe and have few, if any, side effects. Oral PGAs that I most frequently prescribe are Cosequin and Glycoflex. Adequan is an injectable PGA that is also frequently used.
Rest and weight control are two additional treatment modalities for CHD. We ideally do not want to rest or restrict a dogs activity to the point that it limits their quality of life. However, most dogs with CHD have to have their exercise limited to varying degrees in order to lessen the wear and tear on the hip joints. It is also critical that dogs with CHD not be overweight. Obesity by itself will not directly cause hip dysplasia, but it is one of the most significant environmental factors that should be avoided.
Surgery unfortunately is required in many cases of CHD that do not or no longer respond to medical therapy. Though involved and not inexpensive, the surgical options for CHD are often dramatic in returning afflicted dogs to pain free and even athletic life styles. It is beyond the scope of this article to describe the technical aspects of each procedure, but I will briefly overview the most frequently performed procedures. Triple pelvic osteotomies are preventive procedures performed on young dysplastic dogs prior to the onset of degenerative joint disease. There goal is to prevent or at least minimize osteoarthrits. Femoral head osteotomies in my opinion are “salvage” procedures that have a primary goal of decreasing a dogs pain. Total hip replacements are performed on dogs already dealing with degenerative joint disease from CHD. Though expensive and performed at veterinary colleges and referral practices, their results are usually nothing short of dramatic. Dogs that are literally crippled from the effects of CHD can return to a pain-free athletic life after having a total hip replacement. Another great advantage of the surgical options for CHD is that the veterinary profession has grown significantly in our ability to decrease post-operative pain that can occur during recovery from surgical procedures, such as these.
In closing, the treatment options that are available today for canine hip dysplasia have improved dramatically over the past 5-10 years. With the availability of new and safe non-steroidal antiinflammatories and cartilage-protective medications, conservative medical management of CHD is significantly better. Also, with the increased availability of veterinary surgical specialists, surgical options are more viable for those patients who do not respond or are not good candidates for medical management