I think that's mad! Surely that's an entirely flawed system?? How can you trust a hip score done at 12 months that isn't still the case when the dog gets to breeding age. Why are dogs allowed to be hip scored before they're fully developed? I think I smell a rat. Must be all part of the KC approved puppy farmer scheme. DNA test, I completely agree with. That's a constant throughout the life of the dog, but a test that misrepresents the truth is a bit far.
I think that in a way you are right. basically the hip scoring scheme is fundamentally flawed in several ways:
1. You are using phenotype (ie the shape and relationship of the bones as assessed by radiographs) to try to predict genotype (ie if the sire and dam are carriers of the genes that contribute to hip dysplasia). These are not the same as you can have clinically unaffected dogs that are carriers of the genes that can pass them on to some of their offspring
2. The hip score changes with age due to the progression of osteoarthritis in affected dogs. Please also bear in mind that the hip score could be affected by other causes of hip osteoarthritis including trauma which would also lead to deterioration with age
3. As Buchan has rightly mentioned, the hip scoring scheme uses carefully positioned radiographs to assess for signs of hip laxity (hip dysplasia) as well as the secondary effects of hip laxity (osteoarthritis). The defined position used whilst obtaining hip scoring xrays is the ventro-dorsal hip extended view. This has been chosen as it optimises the view of the femoral head and neck. Unfortunately it also twists the joint capsule around the femoral neck which in effect draws the femur deeper into the socket. This will reduce the degree of subluxation of the femoral head and lead to a reduction in the hip score. The effect of this is difficult to quantify and is likely to vary between animals due to differing properties of the joint capsule.
4. Careful positioning can be used to make affected hips appear slightly better.
5. Scoring dogs young will often result in a lower hip score as the degenerative changes are less advanced. Many breeders will have their breeding dogs scored at 1 year of age to reduce the scores as far as possible. This can lead to bad decisions being made. Perhaps breeding dogs should be rescored through their breeding lives to pick up degenerative changes as they develop.
6. Often where dogs are xrayed and found to have bad hips, the xrays will not be submitted as this avoids the fee associated with BVA/KC assessment. This practice is widespread but has the effect of causing bias when calculating the breed mean score
7. The breed mean score is a measure of the average hip score for each given breed. Unfortunately many breeders will regard breeding stock with hip scores below the BMS as having good hips. This is not the case as these dogs may well be carriers of certain genes that will be transmissible. What is needed is for there to be greater selection pressure applied before selecting breeding stock. Using an example of the Labrador with a BMS of 14. Perhaps breeders should be encouraged to only breed from dogs with a cumulative score of less than 4 rather than anything less than 14. This would dramatically reduce the pool of suitable stud dogs but those that are left should have better hips.
There are better ways of assessing hip conformation to determine if hip laxity is present. These are the PennHip scheme and the dorsal subluxation scores. Both of these methods have been developed in the US but have not found widespread acceptance in the UK. These techniques use stressed radiographic positioning to make an objective assessment of hip laxity with is the main predictor of which hips will develop hip osteoarthritis. Unfortunately until fairly recently PennHip has not been possible in the UK due to our radiation protection regulations and the dorsal subluxation score doesnt seem to have caught on anywhere that I am aware of. There is more information online regarding PennHip at
http://research.vet.upenn.edu/Default.aspx?alias=research.vet.upenn.edu/pennhip
Another concept that could be usefully employed is the calculation of estimated breeding values. This would likely involve linking information regarding the phenotype of the proposed stud animal with information gleaned from other animals in their blood line. This may allow some of the carriers that are not showing clinical signs of HD to be weeded out of the breeding population.
Despite these limitations, the BVA and KC have done a sterling job of trying to select appropriate progeny but to be honest, progress has been very slow. Since the canine genome has been mapped, work is being performed to try to identify the genes that contribute to hip dysplasia. As HD is a polygenic trait with complex inheritance patterns, this is incredibly challenging. the hope is that eventually a genetic test will become available to assess the genotype of breeding animals early in the course of their lives. In reality this is likely to be several years away so in the meantime, whilst BVA/KC hip scoring scheme and PennHip may be flawed, they are all we have to work with.
Just a general comment regarding the hip scores as I frequently meet people who are disappointed and even angry where puppies from a litter where the parents had low hip scores develop clinical disease... the hip scores are only like the odds in a horse race, choosing low hip score parents improves the chance of having offspring with good hips, but it is no more a guarantee than the favourite always winning the Grand National.