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 genetic (polygenic) trait that is affected by environmental factors.
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 surfaces 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.
In a hip suffering from dysplasias, 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 have no apparent pain issues. 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.
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.
Although dog breeders have attempted to eliminate hip dysplasia through selective breeding, the reduction of canine hip dysplsia frequency in pure-breed dogs has been disappointing.
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 surfaces 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.
In a hip suffering from dysplasias, 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 have no apparent pain issues. 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.
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.
Although dog breeders have attempted to eliminate hip dysplasia through selective breeding, the reduction of canine hip dysplsia frequency in pure-breed dogs has been disappointing.
Fast facts about Canine Hip Dysplasia from PennHIP
- Canine hip dysplasia (CHD) is the most commonly inherited orthopaedic disease in dogs.
- CHD is a degenerative, developmental condition, leading to painful hip osteoarthritis, stiffness,
and diminished quality of life.
- All dog breeds are affected by the disease, in some breeds more than 50% of dogs are afflicted.
- The disease is polygenic and multifactorial.
- The development of CHD is affected by environmental factors such as weight and age.
- There is no medical or surgical cure for CHD.
- CHD is a major concern for working dogs, pet owners, breeders and veterinarians.
Please see the links section for more on hip dysplasia or to find out how to have your dog hip scored.