By Caroline Cox
Clara Valley Ridgebacks

Following the recent change in the Code of Ethics of the RRCUS, and subsequent discussion, it seemed to me that it would be a useful exercise to discover what is being done in other countries and to relay it to the members. I therefore made contact with as many people as I knew and asked them to write a simple explanation of what is done in their country with regard to screening for both hip dysplasia (HD) and elbow dysplasia (ED). The response from every country I have contacted has been excellent and without exception all are most anxious to know what is being done in other parts of the world.

Therefore, I have reproduced below what each person has sent me. In some cases, such as the UK which has a particularly complicated system, I hope I have been able to explain without adding too many extraneous details. Also, for the United States I have extracted descriptions of GDC, OFA and PennHip from the Web. I do not presume to make any comments on any country´s practices. The purpose of this article is only to inform as many people as are interested so that they can make their own informed opinions.

UNITED STATES

The Institute for Genetic Disease Control in Animals (GDC)

GDC is the only open registry in the U.S. and is modeled after the open registry in Sweden, established by the Swedish Kennel Club. Open means that all submissions are recorded in the database whether they are passed or failed unlike OFA and CERF which are confidential, closed systems. Radiographic Evaluation by experts determines the phenotype (the actual condition) of a dog. Normal does not guarantee a desirable genotype. The GDC helps to determine the ability to transmit a condition to offspring by a study of the phenotypes of relatives, both normal and affected. This is what determines the genotype of the individual dog. The availability of genotypic data will depend on the degree of participation of breeders, breed clubs and the dog-owning public. As the GDC grows, more and more information will be available on specific lines. The purpose of the open registry is to help breeders and owners reduce the presence of genetic diseases in their breeds. Breeders can evaluate the risk for genetic disease transmission...when there is sufficient data on a family of dogs in the GDC registry. By consulting the GDC for studies of the progeny of a dog and of the siblings and half-siblings of any generation, breeders will learn the genetic disease transmission risk of a prospective sire or dam. The best breeding strategy selects low risk versus high risk dogs.

GDC will certify unaffected animals at a minimum age of 12 months and will register affected evaluations without charge at the age of detection. If a dog is showing symptoms, the GDC advises that you obtain radiographic evaluation before 12 months of age. A GDC Normal Certification will then be issued if the evaluation is normal.

The X-ray position for hips is the standard ventrodorsal view of rear legs extended and parallel to each other. The area must include both the sacrum and the stifles. For elbows, the views should be both fully flexed and neutral lateral views of both elbows. To obtain proper positioning it may be necessary to use chemical restraint. Written criteria for evaluating the radiographs is included on the valuation sheet. Veterinarians who evaluate for GDC have acknowledged these criteria and their findings are recorded in the computer. Regular submissions are sent to be evaluated by two different people; if there is agreement, that conclusion is filed; if there is disagreement, it is sent to a third person for consensus. Litter submissions are evaluated by the GDC director himself. A certification number is issued which includes the identification no. unique to that animal, the anatomical site followed by a secondary disease identifier, the age and lastly a letter which certifies the quality of that site is within Normal limits (grade of E, G, or A is added for hip dysplasia).

The Great Pyrenees Club of America actively promotes GDC has revised its Code of Ethics to accept GDC clearances as it recognizes the advantages of having an open registry where all results can be examined and compared. From the information I have gathered, it would seem that results vary very little between GDC and PennHip and GDC and OFA and when there is a variation it more often than not can be attributed to the condition of the film submitted.

Sources: "The Institute for Genetic Disease Control in Animals (GDC): Open Disease Registry"
Instructions for the Veterinarian for Submitting Films to the GDC and Institute for Genetic Diesease Control in Animals www.vetmed.ucdavis,edu/gdc/gdc.htm .

PennHip

(Information taken from an article entitled "What Happens to the PennHIP Radiograph? Technique and Reporting Process" by Fred Lanting* available on the Internet)

This system of evaluation was developed by the University of Pennsylvania in response to breeders need to get an earlier idea of how good were the hips of their canine products.
A puppy may be X-rayed as early as 4 months of age. Only PennHIP-certified vets may submit X-rays and every dog´s films enter the database. One view is the traditional AVMA extended-leg picture for the study of bone abnormalities; another is of the knees-up neutral position with a very small compressive force pushing the femoral heads into the sockets and a third is taken while the dog is deeply under and does not feel anything even on a nearly subconscious level, the patented distractor unit is placed between the legs at the groin, roughly parallel to the pelvis. Twin bars in this device that is shaped like the Roman numeral II act as the fulcrum, and when the lower legs are held near the hocks and pressed together, the vet leverages the femoral heads away from each other and outward (laterally) from the sockets. The films are sent to the Synbiotics PennHIP analysis Center in Malvern, Pa., where a handful of people evaluate them...DJD (degenerative joint disease) presence or absence is noted and circle gauges are laid on the third radiograph for use in objectively measuring the displacement. The results are added to those already in the database and compared. A report is issued that states where this particular dog stands in relation to the average (mean) for its breed, expressed as percentile. For example, if the mean is 0.41 your dog with a DI (distraction index) of 0.53 will be in a percentile between 50 and zero. A percentile of 80 means that your dog has tighter (better) hips than about 80 percent in your breed. The mean varies a little with time and the additon of dogs to the data base. According to Mr. Lanting, there is no evidence to support the feeling that estrus may affect or increase joint laxity. Mr. Lanting recommends breeding only to a partner with higher than 50th percentile and lower DI than the mean or a lower DI than their own dog has, and if [a breeder] really want[s] to accelerate progress [he recommends] to breed dogs with 0.3 or better.

* Mr. Lanting offers seminars on a variety of topics, such as orthopedic disorders, gait and structure, basic genetics, the evolution of the German shepherd Dog and other subjects. He consults on these and behavioral problems and is a multi-breed judge for UKC and AKC and all breed judge for some other registries.

Orthopedic Foundation for Animals (OFA)

OFA is a voluntary registry serving all breeds and has the world´s largest all-breed databank on radiographic evaluations of the hip and elbow status.

To obtain the X-ray of the animals hips, it should be placed on its back in dorsal recumbency with the rear limbs extended and parallel to each other. The knees (stifles) are rotated internally and the pelvis is symmetric. Anesthesia is recommended. For elbows, the animal is placed on its side and the respective elbow is placed in an extreme flexed position.
The X-ray film must be permanently identified with the animals registration number or name, veterinary case or X-ray number, date the radiograph was taken and the veterinarians name or hospital name.It is important to record on the OFA application the animals tatto, microchip number or DNA profile, as required by AKC. Sire and dam information should also be present.
As of January 1, 2001 OFA is requiring permanent identification of all animals submitted to their databases.

Radiography of pregnant or estrous females should be avoided...OFA recommends radiographs be taken one month after weaning pups and one month before or after a heat cycle

If the X-ray is accepted it is given a security hip rating by one of the two radiologists on staff and assigned an application no. X-rays of animals 24 months of age or older are independently evaluated by three randomly selected board certified veterinary radiologists from a pool of 20-25 consulting radiologists throughout the U.S.A. in private practice and academia. Each radiologists evaluates the animals hip status considering the breed, sex, age, and conformational differences and assigns a hip rating. Seven classifications are needed in order to establish heritability information (indexes) for a given breed of dog. Definition of these phenotypic classifications are: Excellent - deep seated hip ball fitting tightly into a well-formed hip socket with minimal joint space. Also there is complete coverage of the hip socket over the hip ball. Good - slightly less than superior but a well formed congruent hip joint with ball fitting well into socket and good coverage. Fair - minor irregularities, a wider hip joint with ball slightly slipping out of the socket. May also show slight inward deviation of the weight bearing surface of the hip socket causing hip socket to appear slightly shallow. Borderline - no clear cut consensus between the radiologists. Usually more incongruency present than in Fair, but no arthritic changes present. May also be a bony projection on any of the areas of the hip that cannot be accurately assessed as being arthritic changes. Mild - significant subluxation and the ball is partially out of the hip socket which is shallow and only partially covers the hip ball. Usually no arthritic changes. Option to resubmit later. Moderate CHD - significant subluxation present where the hip ball is barely seated into a shallow hip socket. Secondary arthritic bone changes usually along the femoral neck and head, acetabular rim changes (bone spurs) and signs of sclerosis. Severe - marked dysplasia exists. Significant subluxation present where the hip ball is partly or completely out of a shallow hip socket. Secondary arthritic bone changes along the femoral neck and head, acetabular rim changes and large amounts of abnormal bone pattern changes. The final hip grade is determined by a consensus of the three independent outside evaluations. Excellent, Good and Fair are given OFA numbers and entered into the registry. The remaining grades are reviewed by the OFA radiologist and a report generated documenting the abnormal findings. All failing grades are closed to public information.

Preliminary X-rays may be submitted on puppies as young as 4 months for evaluation, but to obtain an OFA number these would have to be re-X-rayed at 24 months.

For elbows, it is a simple pass or fail. Abnormal elbows are reported as Grade I - minimal bone change along anconeal process of ulna; Grade II - additional bone proliferation along anconeal process and subchondral bone changes, and Grade III - well developed degenerative joint disease with bone proliferation along anconeal process. As with hips, a preliminary X-ray may be taken, but to obtain certification the dog would have to be re-X-rayed at 24 months.

Source: What happens to a radiograph at the OFA: The submission and Evaluation Process, Frequently Asked Questions, www.offa.org.

Effective July 1, 2000 the OFA will institute owner choice pertaining to an open or semi-closed database for the hip, elbow and patella databases. The open database will provide all information (normal & abnormal) in the public domain. The semi-closed database will provide only normal data in the public domain. If the owner fails to choose a specific database the results will automatically default to the semi-closed database.

Source: Bonnie Loudon, Corresponding Secretary, RRCUS.