What’s the cause of hip dysplasia?
Canine hip dysplasia is an inheritable disease. Its mode of inheritance is termed “polygenic,” meaning that it is due to a combination of multiple genes. Because of the polygenic nature of this disorder, some normal dogs.

(Those that hip tested clear ) produce a percentage of dysplastic offspring. The breeding pair, although physically normal, may each transmit some of the dysplastic genes to their offspring, thus the offspring may receive a combination of complementary and uncomplimentary genes from both parents ( it’s those little hidden recessive genes) which may cause hip dysplasia in a pup bought from hip tested clear parents.

The division of defective genes is very uneven, with one parent contributing more defective genes than the other. Environmental factors such as a high caloric diet during the rapid growth phase of a puppy can exacerbate the changes in dysplastic hips, but cannot create a dysplastic. dog Hip dysplasia occurs when it’s not fit properly into the pelvic socket. This condition, while not present at birth, develops. Hip dysplasia is an abnormality of the hip joint in which the head of the femur goes during the first two years of the dog’s life.

It is often progressive, causing inflammation, pain, and arthritis in one or both hips. Symptoms may range from mild to severe and can be aggravated by strenuous exercise. Though they are at risk for hip dysplasia, the Siberian Husky ranks relatively low when compared to other breeds out of the 136 breeds of dog tested for hip dysplasia. The husky ranks 134th, with only a 2% chance of having Hip dysplasia. Hip dysplasia is an abnormality of the hip joint, typically the ball and socket of the joint becomes deformed, meaning the ball joint does not sit and fit correctly into the socket properly , which in turn can lead to arthritic problems in later life, in extreme cases mobility can be effected from an early age.

KC/BVA Hip-Scoring Scheme

In recent years, there has been a trend towards X-Raying and scoring of breeding stock in order to ensure that only those animals with acceptable hips are used for breeding. The scoring scheme allows for each animal to be graded according to a set of pre-defined criteria. The scoring range is from 0-53 on each hip (0-106 in total) where 0 represents perfect hips and 106 represents the worst scenario. This average score is often lowered and will probably change even more as more dogs are scored. The current average for the breed is always given with the BVA sheet returned with the X-ray.

Interpretation of Hip-Scores however, it must be recognized that hip dysplasia is not a black and white issue. It is not a matter of whether a dog has or has not got the problem, but rather the extent to which it has the problem. Any mating which uses an animal below the breed average, has the potential to improve the overall state of the breed, with regard o hip dysplasia. Similarly, use of an animal with a score above the breed verage should not necessarily be condemned providing the immediately preceding enerations are of low-score and an effort has been made to use a low-scoring tud dog. It is not uncommon for parents with good hips to produce offspring ith poor hips as there may be ancestors in the pedigree with poor hips and this can come to the fore in a subsequent generation.

Occasionally, puppies produced from several gnerations of low-scoring ancestors can still be affected. It is important note that veterinary research indicates that there is also an environmental Influence on the incidence of HD. Poor management of the growing dog will relevant it reaching its maximum potential in terms of hip status. Over-exercise, ver-feeding, excessive use of vitamins and supplements can all have an adverse effect on the development of bones and joints

+FACTORS AFFECTING HIP DYSPLASIA AND SCORING

M.B. Willis
Positioning: Tilting of the X-ray to the side or forwards towards the camera will adversely affect the score to some degree. There may even be uneven scoring in terms of right vs left side and extra 3 or 4 points depending on the degree of lift. The effect will be largely on the first three items. Tilting is unlikely to effect the last six items to any degree. For an in depth look at this topic please take a look at www.leerburg.com

Reader: Readers can differ slightly in interpretation. The BVA use two readers from a panel of 9 or 10 selecting fairly randomly. All panelists are Diplomats of Veterinary Radiology (DVR) and thus highly experienced. Nevertheless even they can differ slightly in their interpretation of plates. If a user feels that the score was wrong then appeals are dealt with by their chief scrutineer.

Anesthetic: Recent information suggests that anesthetics can give rise to greater joint laxity than will sedatives. Thus a dog that is anaesthetized MAY show a higher score for Norberg angle and Subluxation than the same dog would if merely sedated. Most schemes seek to anaesthetize dogs and thus all are being compared on valid terms. If however, a breeder is submitting animals that are sedated it could lead to slightly lower scores and thus apparently better results than rivals who are using anesthetics. This must be borne in mind when considering score data.

Sex: In man, female children are at greater risk of HD than males. In the dog it looks as though a similar status exists. In most breeds with enough data females score some 3-4 points higher than do males. This has nor been observed in OFA data but is seen in British, Australian, and Scandinavian data for the majority of breeds.

Age: In OFA data a large age effect is claimed. With scoring the effect appears to be much less. For every month of life after 12 months hip score increased by from 0.07 to 0.17 points. This is quite small and suggests minimal age effect in score data. However, good hips will show almost no change while poor hips may show a larger effect. Breeders are urged to score as soon after 12 months but larger breeds might be better at 18 months.

Breed: Breed effects are known, with some breeds at high risk others low. The belief is that this was associated with growth rate or 60 day-weight is now less tenable. Although larger-sized breeds generally tend to be more prone to HD than smaller sized ones this is not inevitable.

Exercise: This is unclear but excessive exercise in early puppy hood seems unwise. If one had bred for bad hips then a failure to exercise will not necessarily prevent HD occurring. In dysplastic dogs exercise is necessary to maintain muscularity which will be lost if the dog is not exercised. Such dysplastic dogs need exercise little and often, preferably lead work on hard surfaces.

Synovial fluid: This is a lubricant in joints. Excess synovial fluid is implicated in HD particularly through hyaluronic acid, a component part of the fluid, where a reduced concentration is associated with greater HD.

Hormones: Hormones are thought to influence HD but evidence is unclear. However it is known that SOME bitches will show greater joint laxity during oestrus and thus score higher. It is recommended that for this reason bitches NOT be X-rayed for the scheme during oestrus

Vitamin C: There is no evidence that Vitamin C is implicated in HD. Indeed use of large amounts of vitamin C to combat HD is contra-indicated and not recommended. Breeders are therefore urged not to use Vitamin C in a belief that HD will be avoided. It will not be!

Unilateral Hip Dysplasia: In all breeds some 80% or more of dogs differ by four points or less between hips and thus HD largely a bilateral state. However, some dogs score unevenly. At times this is a positional feature but in some it is not.

Dogs can score unevenly because of trauma (injury) or due to transitional segments on the spine but a proportion of dogs are uneven and will breed this feature on

Breeding: Breeders should select as good a hip as they can in both males and females, bearing in mind breed average. The lower the hip score the better the broad terms but they should look at the where points are scored and try not to use animals scoring over 3 in any one place and certainly not mate animals where both score high in the same features.

The individuals own score must suffice initially but a good hipped dog from a good pedigree (parents / grandparents) is a “better bet” than one with a less good pedigree. Dogs with good litter mates are also potentially safer than dogs with poor litter mates and to this end the scoring of litter mates, whether show dogs or pets, is desirable as an aid to breeding. However, once progeny data are available on sufficient progeny this is more useful than the data on the animal or its pedigree/litter mates etc.