The Orthopedic Foundation for Animals maintains a list of top 100 + breeds affected by hip dysplasia, Staffordshire Bull Terriers are # 63 out of #190. The number #1 breed has the most hip dysplasia results reported and number #190 has the least, we sit pretty high on the list at #63 for having a high percentage of hip dysplasia reported.

In dogs, 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. It is common in many dog breeds, particularly the larger breeds or dogs with heavy BMI, and is the most common single cause of arthritis of the hips.

Dysplastic hip anatomy
The hip could have major contractions or seizures from dysplasias. The spherical end of the femur head(the ball) 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 ball of the femur head 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, the more the joint becomes damaged, the less able it is to resist further damage. The inflammation causes even further damage. The bones of the joint may also develop osteoarthritis, visible on a radiograph as small outcrops of bone, which further degrade the joint. Osteoarthritis is a degenerative disease marked by the breakdown of
cartilage between joints resulting in painful bone-to-bone contact.

The underlying deformity of the joint may get worse over time, or may remain static. A dog may have good radiographs and yet be in pain, or may have very poor radiographs 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 (lack of 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 also plays a role. To what degree the causality is genetic and what portion environmental is a topic of current debate. Neutering/Spaying a dog, especially before the dog has reached an age of full developmental maturity, has been proven to almost double the chance he or she will develop hip dysplasia versus intact dogs or dogs that were neutered after reaching adulthood. Other environmental influences include overweight condition, injury at a young age, overexertion on the 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 may help provide procedures to effectively reduce the occurrence of this condition. Hip dysplasia screening is readily available through the orthopedic foundation (OFA) or Pennhip, using specific hip radiograph technique.