Understanding Hip Dysplasia

   Canine hip dysplasia is a very common degenerative joint disease seen in dogs. There are many misconceptions surrounding it. There are many things that we know about hip dysplasia in dogs, there are so many things we suspect about this common cause of limping, and there are some things that we just do not know about the disease. 

   
 What is Hip Dysplasia?

   To understand what hip dysplasia really is we must  have a basic understanding of the joint that is being affected. The hip joint forms the attachment of the hind leg to the body and is a ball and socket joint. The ball portion is the head of the femur while the socket is located on the pelvis. In a normal joint the ball rotates freely within the socket. To facilitate movement the bones are shaped to perfectly match each other, with the socket surrounding the ball. To strengthen the joint, the two bones are held together by a ligament. The ligaments the femoral head directly to the acetabulum. Also, the joint capsule, which is a very strong band of connective tissue, enccircles the two bones adding further stability. The area where the bones actually touch each other is called the articular surface. It is perfectly smooth and cushioned with a layer of spongy cartilage. In the normal dog, all of these factors work together to cause the joint to function smoothly and with stability.
    Hip dysplasia results from abnormal development of the hip joint in a young dog. It may or may not be bilateral, affecting both right and left side. It brought about by the laxity of the muscles, connective tissue, and ligaments that should support the joint. Most dyslastic dogs are born with normal hips but due to genetic and possibly other factors, the soft tissue that surround the joint starts to develop abnormally as the puppy grows The most important part of these changes is the bones are not held in place but actually move apart. The joint capsule and the ligament between the two bones stretch, adding further instability to the joint. As it happens, the articular surfaces of the two bones within a joint is called subluxation and this , and this alone, causes all of the resulting problems we associate with the disease.


    

Hip Dysplasia Pictures

 When a dog has hip dsplasia, the ball and socket do not fit smoothlty. The socket is flattened and the ball is not held tightly in place thus allowing for some slipping. This makes for a unstable joint and the body's attempts to stabilzze the joint only end up yielding arthritis.

Normal hip- femoral head hits snug inside acetabulum

This is a early stage of hip dysplasia. Note: the space betewwn femoral head and acetabulun

This dog has hip dysplasia but has not yet developed arthritis. Note: the shallow hip sockets. This is a x-ray of a young dog but this dog shows up as a elderly dog

What are the symptoms of hip dysplasia?
 
   Dog's of all ages are subject to the symptoms of 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 vigorous exercise. The condition will worsen until even normal daily activities are painful. Without intervention, these dogs may be unable to walk at all by a couple of years of age. In most cases, however, the symptoms do not begin to show until the middle or later years in the dog's life. 
   Dogs may walk or run with an altered gait, often resisting movement that require full extension or flexing 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. Most dogs will warm up out of the muscle stiffness with movement and exercise. Some dogs will limp and many will decrease their level of activity. AS the conditions progresses, the dogs will lose muscle tone and may even need assistance in getting up.

Who get hip dysplasia ? 

   Hip dysplasia can be found in dogs, cats, and humans. In dogs, its primarily a disease of large and giant breeds.The disease can occur in medium-sized breeds and rarely even in small breeds . Its primarily a disease of purebreds although it can happen in mixed breeds, particularly if it is cross of two dogs that are prone to developing the disease. German Shepard's, Labs, Rottweilers, Great Danes, Goldens, and Saint Bernard's appear to have higher incidence, these are all very popular breeds and may be over represented because of their popularity.

What are the risk factors for the development of hip dysplasia? 

  Genetics - Almost all researchers agree that there is a genetic link involved. If parent has hip dysplasia, then the offspring are at greater risk for developing hip dysplasia. If you you bred two dysplastic dogs, the offspring are much more likely to develop the disease but will not all have the same level of symptoms or necessarily show any symptoms. the offspring from these dogs will, however, be carriers and the disease may show up in their offspring in later generations. We can greatly reduce the incidence of hip dysplasia through selective breeding and screening.

 Nutrition:  WE can increase the severity of the disease in genetically susceptible animals in a umber of ways. One of them is through obesity. It stand to reason that carrying around extra weight will exacerbate degeneration of the joint in a dog with loose hip. Overweight dogs are therefore at much higher risk. Another factor that may increase the incidence is rapid growth in a puppy during the ages from three to ten months.

Exercise: Exercise may be another risk factor. It appears that dogs are genetically susceptible to the disease may have an increased incidence of the disease if they over- exercised at a young age. But at the same time, we know dogs with large and prominent leg muscle mass are less likely to contract the disease than dogs with small muscle mass. So exercising and maintaining good muscle mass actually decrease the incidence of the disease. Moderate exercise that strengths the gluteal muscles, such as running and swimming, is probably a good idea. Whereas, activities that apply a lot of force to the joint are contraindicated. An example would be jumping activities such as playing Frisbee.


   I hope this help you and understanding hip dysplasia in dog. If you need more information on this disease please check out the OFA web site: Orthopedic Foundation for Animals or PennHIP: University of Pennsylvania Hip Improvement Program.
         
        Orthopedic Foundation for Animals- www.offa.org
        Pennsylvania Hip Improvement- www.pennHip.org