HIP DYSPLASIA
TWO FACTORS DETERMINE WHETHER HD WILL OCCUR
It is known that two factors determine whether HD will occur, and if so, how bad it will be. These are hereditary and ‘environmental’ factors. ‘Hereditary’ relates to the genetic code passed to the offspring by both parents and environmental are all the outside influences which alter and shape the growth and functions of the bones, cartilage, ligaments, tendons and muscles of the body. In simple terms the genetic code is rather like an architect’s plan (genotype), while the environment is like the builder and his materials (phenotype). In HD the architect has made some errors but the builders have a great influence on how things finally look and function.
As the breeder we are the architects and endeavour to breed from the soundest dogs we can. All our dogs are x-rayed and scored for hip dysplasia. Because our breeds are know to have incidents of the disease occur it is extremely important that our puppy buyer’s take on their role as the builders with extreme importance. They are responsible for never allowing their charges to become overweight, to feed them properly on our suggested diet, not give any unnecessary nutritional supplement s and not to over exercise their puppies. They need to be diligent in preventing injury and recognising potential hazards.
Please read the information on HD that we have provided, as we think whether you are purchasing a puppy from us or other breeders, or simply wanting to know more about the problem, it will give you a better understanding re acceptable HD scores and that even good scores don’t guarantee a non affected animal. Plus understand that owners have to be prepared to put the effort into correct raising from puppy to adulthood also.
UNDERSTANDING HD SCORING
As responsible breeders we screen all our breeding stock for Hip Dysplasia and follow the BVS (British Veterinary Association) recommendation on choosing parents that adhere to their advice.
Hip Scoring should be considered along with other criteria as part of a responsible breeding programme, and, ideally, breeders should choose breeding stock with hip scores WELL BELOW the Breed Mean Score (BMS) and ideally below the Median for their breed.
BVA HD SCORES
DATA CACULATED TO 01/11/2011
| BREED NO | RANGE | BMS | 5YR MEAN | MEDIAN | |
| NEWFOUNDLAND | 4337 | 0-106 | 25 | 20 | 15 |
| RHODESIAN RIDGEBACK | 2322 | 0-88 | 11 | 9 | 8 |
The Breed Mean Score (BMS) represents a global mean of the scores of all dogs of that breed that have been through the Hip Dysplasia
Scheme up until 31st October 2011. The Median Score has been calculated from data recorded on the Kennel Club’s electronic registration database, up until 31st October 2011. The 5-year mean is the mean of all hip scores recorded on the Kennel Club’s registration database for the recent 5 year period.
CLICK BELOW HIGHLIGTHED LINK TO READ BVS LEAFLET ON HD
Hip_Dysplasia.pdf (441,7 kB)
BRIEF OVERVIEW OF HIP DYSPLASIA
Hip Dysplasia
The Disease
Hip dysplasia is neither a new disease nor one exclusive to the dog. It has been known in man since Roman times and has been found in the horse, the cat and beef cattle. The discovery in dogs was made by Schnelle (American veterinarian) in 1935.
The condition has been variously called subluxation, acetabular dysplasia, congenital hip luxation and congenital hip dysplasia. The more usual term is hip dysplasia since congenital implies that the disease is present at birth and this is apparently not the case in the dog although it is in man.
The disease is, as the name implies, a problem of the hip joint. This is a ball-and-socket arrangement with the femur head (ball) fitting tightly into the acetabulum (socket) in a normal animal. Abnormalities which may occur in this joint vary in both severity and in the nature of the secondary changes that occur as a result. The basic problem is one of a shallow acetabulum or of a laxity of the joint in the sense that the tissues holding the femur head in place are relaxed and as a result luxation occurs. It seems that joint laxity is a more logical cause of the problem. Subluxation may be minor or severe and in more severe cases there may be alteration of the surfaces of both acetabulum and the femur head caused by friction between the two. In very severe cases the damage to the bones may become such as to lead to wearing away of the femoral head and extremely shallow acetabular sockets.
Diagnosis
When one comes to diagnose the disease it is important from the outset to realise that no accurate diagnosis can be made without an x-ray being taken. Clinical diagnosis based upon gait is imprecise and can be positively misleading. I have seen some very severe cases of dysplasia which were so badly affected that they could not turn at right angles without first falling over. But I have seen others which were capable of moving with a degree of soundness that would win in the ring. The breeder or veterinarian who looks at a dog and dismisses it as dysplastic on the basis of an unsound gait or as normal on the basis of sound gait is being extremely foolish. With breeds that have a high incidence of the disease one is on fairly safe grounds saying that every dog is affected, certainly one will be right more than one is wrong, but this is a misleading principle. By all means suspect the dog with a kind of stilted gait, or the one which bunny hops from choice, or the one whose croup switches from side to side while the animal is walking. But never allow physical appearances to override the need for an x-ray. Just because a dog takes a lot of exercise does not mean that he must be free of hip trouble, even a good jumper might have some degree of dysplasia although it is very unlikely that a good jumper is severely dysplastic. X-ray and only an x-ray is the sure way to diagnosis.
Prevention
The first thing to accept is that we are dealing with a polygenic trait with a heritability of around 25 to 30%. This means that the selection procedure has to be on of using the best available hips from those dogs which are structurally and temperamentally worth breeding from. The emphasis must first be on structure and character and secondly on hips because the object is to breed typical specimens with increasingly better hips. It is not to breed good hips in dogs which may or may not be good specimens. If one uses a scale grading hips and the breed average were, let us say grade 3 while the average of the selected stock was grade 1 then the average of the progeny other things being equal, would be expected to have improved by 0.6 of a grade. This is a small improvement per generation and may not be easily measured but in time it should be apparent that progress is being made.
In discussing methods of improvement it must be remembered the important thing to accept is that not all normal dogs give equally good results in their progeny.
(Information in this article was taken from M B WILLS B.SC PhD book titled “The German Shepherd Dog, Its History, Development and Genetic)