Hip Methodologies around the World
The importance of health clearances is generally known and embraced by the ethical breeding world. However, there is a great variety of clearances depending upon breed and methodology of evaluation based upon club or Country of origin. In this article I will try to explain a bit about the different means of evaluating hips.
The purpose of evaluations is to know what the given condition of an animal used for breeding is at the age of breeding. Using known evaluations on animals and selectively pairing can help to improve the overall statistic of healthy joint configuration. In golden retrievers the statistical ratio of animals affected by hip dysplasia is about 20%. There is some variance of this statistic because 1) not all animals are tested, and 2) some animals who are tested are not registered on the data base. Having parental lineage with 'clear' hips does not guarantee a puppy with clear hips; but it does help to improve the overall incidence rate in the breed. As ethical breeders, we are charged with making judgement calls to improve our breed. Hopefully a further step is providing an enforceable guarantee that insures puppy families that you stand behind your animals.
Also as the European Veterinary medical community has been saying for years, we are now hearing Vets here agree that it is not only genetics, but nutrition as well. Here is a link to a great article: Hip Dysplasia Causations
Also, a new study I just was given that further suggests the environmental issues affecting hips. Lots of consensus building to hold off on spay/neuter until 1 year of age. See UC Davis study: here!
I'll just further add to that the importance of a proper large breed formula if you have a large breed puppy. I know not everyone finds it fascinating to read dog nutrition labels like I do - so I'll give you the cheat sheet. The calcium level that is appropriate for Large Breed puppies is about 1.1 to 1.3% NO HIGHER THAN THAT! The Phosphor level works in careful conjunction with that number. If you calcium is on the 1.1 level, your phos should be about .9...if its closer to the 1.3 mark then I would expect to see a number around .95% I personally will not feed, nor advise for my puppy families ANY food that varies from those margins. A protein number that is in excess of 28% is also way to much for a puppy's needs. There are some Super Premiums that have excessively raised protein to impress YOU. Feed the dog and know what the numbers should be.
OFA or Orthopedic Foundation for Animals - This body hosts, in database form, health statistics for a variety of health clearances. They are also the evaluators for Hip and Elbow certifications for their database. Evaluations are performed on animals from 12 months to two years for 'Preliminary certificate' or after the age of Two years for a final Certificate. Their guidelines for breeding animals include; Excellent, Good, and Fair for unaffected status. A score of Borderline would be suggested for further testing in six months. Scores of Mild, Moderate, or Severe would be applied to animals who the evaluators felt showed some sign of dysplasia.
The Preliminary certificate is examined by one Practitioner. The final Certificate is given an overall score based upon three Evaluator's opinions as to the condition. The overall joint formation is taken into consideration, but no baseline of comparison is given. Criterion of failure are noted as subluxation, but gradations of the differences between grades are not quantified. In other words you get a SUBJECTIVE opinion as to each evaluator's assessment of the condition of the joint. No measurements are taken and the average of the three assessments are made to attain a final score. This was formerly the only method of evaluation in America until Penn University developed their test.
It should be noted that in this method human error of evaluator and human error of xray do potentially play a role. This is currently the most popular methodology because it has been around the longest. Here is an article though that calls to question what some breeders have been suggesting about the reliability of OFA results for some time now: OFA article
Penn Hip - This is a slightly different approach on what will constitute hip dsyplasia in an existant or future likelihood of development model. They do not have stated grades, rather a 'Distraction Index' which is based upon two xray views; one where the joint is fully involved into the socket, another view where the joint is pressured out of the joint to determine a measurement of laxity. The difference between the two films is measured and quantified then applied a position in the overall database as better than 90% of animals etc. There is not a 'Pass/Fail' per se, rather a recommended mean within a breed's average which you should strive to breed improved upon.
This method is purely OBJECTIVE in that opinions are not relevant to the score. There is no variance based upon human input other than (and this could play a part!) the quality of the Xray taker's skill. The overall formation of the joint structure is NOT evaluated, rather the viewpoint is based solely upon laxity being the indication of future performance or condition of the joint. The controversy of this method is that younger animals are possibly more loose in joint than older ones are. Animals in better muscularity have potentially tighter joints. Animals in estrus or leaving estrus have hormonal laxity and could give false laxity measurements. This is a closed database and so while means for the breed are established, reporting is solely breeder based.
England's Method - used widely in the UK and Europe
The BVA - or British Veterinary Association is the keeper of statistics on health clearances as well as the evaluative body. In this method the hip joint is comprised of 9 different elements each of which has an individual and interdependent formation. Each hip is scored and the totals combined to make an overall score. The mean for the breed is established and its recommended that you breed better than the mean - there is no Pass/Fail and there is an open database for verifying clearances (though I think if your dog is domestically bred import, I'm not sure the database hosts the score). The evaluation contains the good points of both American methods in that it looks at the entire hip joint and evaluates in a quantitative, non-subjective manner.
In the 9 components of a hip joint, each is scored on a scale of 0, meaning perfect to 6, meaning the worst conceivable. Each score has an absolute definition - there is no room for variance - they are all defined. Because of the clearly defined information and definition, there is little room for opinion to taint this method. Because the entire joint is taken into consideration and not merely one aspect; configuration or laxity - you get a truer indication of evaluation.
Link to thorough description with diagram of hip joint of the definitions and scoring of a BVA hip score: BVA Info
As a breeder I have used all three methods. I think that every breeder must make judgement calls based upon what is best for their animals, pairings, programs and the future of the breed. There is plenty of mud slinging going on out there and I'm sure explaining the methods won't stop that, but in educating people about the methods perhaps we can all work towards breed score improvement. I think the BVA method alone allows for specific shortcomings in joint configuration to be remedially paired for improvement. More data equals more tools to use to better. For example; you have stud with a perfect O on 'Cranial Acetabular Edge', but you have a girl with perhaps a 4 in that component. Wouldn't you have a better chance of remediating that flaw with a corrective pairing than merely breeding and Excellent to a Fair? Its simply more data for consideration. You would aim for pairings that related to the lowest possible score and you would shy away from pairings where, for example, both animals scored 4, 5 or 6 in one component. This is how we gain improvement on a scientific basis.
I invite a European breeder to write up the FCI methodology which I know the least about. It is comprised of an A B C or D grade. A's and B's are passing. C is borderline to mild, but permissable with a remedial pairing, and D's are fail.