HIP SCORING IN THE UNITED KINGDOM
In 1983 the British Veterinary Association and the Kennel Club developed a scheme to assess the degree of hip malformation of dogs through radiography. However the scheme in it's present form has been running since 1978.
There are currently 100 breeds surveyed by the scheme in the U.K.
The first scheme awarded a status of either Pass or Fail, this was then followed by a scheme of Pass, Fail, or Breeders Letter, and in 1984 the scheme as we know it today was introduced, which is an assessment on nine criteria, and scores of between 0 and 6 are allocated for all the criteria with the exception the caudal acetabular edge which has a maximum score of 5.
The best score that can be achieved is 0 - 0 which means after each radiograph for each hip has been evaluated there is no abnormality. The worst score then is 53-53. The two are then added together to give a total hip score.
The British system of scoring x-rays for hip dysplasia has an advantage over scoring schemes used in other countries because we assess a number of specific anatomical landmarks which ensures a relatively objective evaluation for each joint. The hip joint is a complex one; it is this particular joint that transfers power from the hind leg muscles to the body, with the supporting structures of ligaments and tendons, the hip becomes a unit. The surfaces of cartilage are lubricated by joint fluid which ensures a pain free action.
Under the Kennel Club / B.V.A. scheme a dog may be x-rayed and scored. The dog must be over one year old to be hip scored, and there is no upper age limit. The dogs Kennel Club Registration Number must be recorded on the x-ray and the Left and Right side must also be marked. It is important that the radiographs are clear and of good quality, with good contrast, and with no under or over exposure. For this reason dogs are x-rayed under anesthetic, it is helpful to relax the dog, and achieve better positioning. It is unrealistic to expect that excellent radiograph technique will always be consistent, so it is therefore sometimes necessary to make compromises when allocating scores. When it comes to image interpretation it is recognized that even experienced observers can make mistakes in the evaluation of abnormalities, to minimize this error there are two scrutinizers to examine each radiograph.
So what is Hip Dysplasia? In basic terms the hip joint is a ball and socket joint, the ball being the femoral head, and the socket the acetabulum. Hip Dysplasia is a malformation of the hip joint, when the head of the femur is no longer seated correctly in the socket.
There is no predicting, just by looking from the outside, to what a degree a dog has or hasn't got H.D. The only way to assess properly the presence or absence of H.D. is by radiography. If H.D. was caused by a single factor then it would have been fully understood and overcome by now. Genetic and environmental factors influence the development of Hip Dysplasia, and affect the final degree of lameness and disability.
Some of the environmental factors to consider are diet. The feeding of a diet that result in excessively heavy puppies at a young age can lead to the overloading of soft cartilage in the developing joints and can result in the deformation of the predisposed dysplastic joint.
Over exercising of dogs with unstable joints will accelerate wear and tear of the hip. Short and frequent exercise will allow the joint to adapt and become more stable and pain free by the time the dog is an adult.
Hip Dysplasia is a most complex subject, as is it's mode of inheritance, it is widely believed that most cases are hereditary, and it is advisable to acquaint yourself with the status of hips within the breed. Information obtained from the Kennel Club recently indicates that for the Chow Chow the breed mean score about 14. Advice from the B.V.A. states that in order to improve the hip status of the breed, only animals with scores below the breed average should be bred from. Dogs with a good hip score can still produce dysplastic puppies though.
Hip dysplasia is not caused by a simple recessive gene that can be bred out in a couple of generations, but research has shown that it can be greatly reduced by using breeding stock that have clear, or a low hip score. Some people won't have their dogs x-rayed because they will not risk putting their dog under anesthetic. Today's medical advances have developed many kinds of short term anesthetics that are considerably safer than before. The risk of losing a dog during hip x-ray is no greater than during surgeries for cesarean or entropian.
From the fact sheet obtained from the Kennel Club, over one hundred and twenty two thousand dogs have been hip scored, the Labrador Retriever having had more than twenty eight thousand scored and the German Shepherd dog over twenty seven thousand. I don't know what these two breeds registrations have been over the last 15 years, since the present scoring scheme was introduced, but nearly twelve and a half thousand chow puppies have been registered with the kennel club during this time, and as at the end of October 1998 only 573 had been hip scored.
In 1983 when the scheme was started you sent in the x-rays and if your dog scored no more than 4 in total, but with neither joint giving a score of more than 3; you received an H.D. Certificate from the Kennel Club. The scores were never disclosed in the Breeders Register though. If your dog scored more than 4 you just never got the H.D. Certificate. Below are the Chow Chows that were hip scored and did receive H.D. Certificates:
Soomar Tanya Edlen Duke Wellington of Bearcat
Cherrymount Cherokee Edlen Special Brand of Bearcat
Lordoch Starblaze Chilite Wendaway
Serobo Heidi Weiyen Hijinks
Shelken Topsy Towmena Silhouette
Kyong Chinese Jade of Bearcat Duarte of Weircroft
Jo-San Jowtrix Jaxartes
The scheme also offered Breeders Letters for dogs that were hip scored and scored no more than 8 in total, but with neither joint giving a score of more than 6. Below are the Chow Chows that were hip scored and did receive Breeders Letters:
Roxanna of Towmena Shadsu Fire Dancer
Zara of Bearcat Bearcat Lolita
T’Sampa Snuffles
Information kindly sent to me by Chris Clucas.
This is a link to the B.V.A. website that gives further up to date information on hip scores in the UK. http://www.bva.co.uk/public/chs/bms2006.pdf