Canine Health Registries
Genetic Disease Control: The Open Registry is Here, The Time is Now.
by Paul Poulos Jr. DVM, Ph.D., Diplomate ACVR
This article appears at the direction of the NCA Board of Directors to help acquaint the membership with the concept of the open registry.
At its November 1997 meeting, the NCA Board endorsed a policy to encourage the use of an open registry as a means through which the membership could share health-related information, and Supports participation in the registry for the health of our Newfoundlands. For more information on this decision, please read the minutes on pages 48-49. See also 1st Vice President Beverly Eichel's article on page 51, which details the background leading to the Board's recommendation and endorsement of open registries.
Who better to tell us about one such open registry- The Institute for Genetic Disease Control in Animals (GDC)-than the president and CEO of the GDC, Paul Poulos, Jr., DVM, PhD., Diplomate ACVR. Dr. Poulos originally wrote the following article to explain the open registry concept as a means of identifying the genotype of affected animals for various breed clubs.
Dr. Poulos is a consulting radiologist from Potter Valley, California. A diplomate of the American College of Veterinary Radiology, Dr. Poulos is currently operating a consulting practice in radiology and ultrasound in northern California. A graduate from the University of California-Davis, Dr. Poulos earned his small animal practice VMD (the Swedish equivalent to a PhD.) in comparative pathology from the Royal Veterinary College in Stockholm, Sweden in the study of Osteochondrosis, served as an associate professor of radiology at the University of Utrect in the Netherlands, was a professor and chairman at the University of Florida in Gainesville of both the departments of radiology and of comparative and experimental pathology.
In the past 40 years veterinary medicine has advanced the frontiers of diagnosis, preventive medicine and nutrition to a new state of the art. But we have advanced little in the area of genetic disease control. Today we understand that many of the diseases that confront us have a basis in genetics. Some are obvious and the mode of inheritable is known. There are many others, however, where either the mode of inheritance is unknown or a genetic basis unproven. Many veterinarians have been trained in institutions where the study of genetics was not stressed. In fact, there are less than two hundred veterinary geneticists world-wide.
In 1987, Dr. Donald Patterson (Professor of Medicine and Chief of the Section on Medical Genetics at the University of Pennsylvania, School of Veterinary Medicine) wrote an article for the AKC Gazette in which he proposed the establishment of "The Canine Genetic Disease Information System." This system is a computerized library of known and suspected genetic diseases, listed by breed and cross referenced. It is not yet available at the time of this writing. He went on to state that the next step should be the establishment of "a comprehensive certification for genetic diseases."
The next step has been taken. The Institute for Genetic Disease Control in Animals (GDC) offers a comprehensive certification for genetic diseases.
GDC and similar open registries in northern Europe provide the only viable means of identifying the genotype of affected animals. The dog owning public, responsible breeders and the scientific community are now demanding not only registries to identify phenotypic affected and unaffected, but open registries which will aid in identifying both phenotype and genotype. In fact, it was the prevalence of elbow dysplasia in Bernese Mountain Dogs that led to the first International Elbow Working Group and the eventual formation of the first open registry for multiple orthopedic diseases in the United States, The Institute for Genetic Disease Control in Animals. The GDC is modeled after the open registry in Sweden which was established by the Swedish Kennel Club working with concerned veterinarians.
Since the establishment of the GDC in 1990, several breed clubs came forward with both support and requests for expansion of the original orthopedic registry. It was the Poodle Club of America working with the Genodermatosis Research Foundation that requested that the GDC establish an open registry for sebaceous adenitis-the world's first open soft tissue registry. It was also the Poodle Club that voted unanimously to establish an open eye registry to include the heritable eye diseases of all breeds. In 1993, the Cairn Terrier Club of America requested the establishment of open registries for Legg-Perthes, craniomandibular osteopathy and medial patellar luxation.
These registries are currently utilized by many breeds in which these diseases exist and have a similar mode of inheritance. In 1994 the Bernese Mountain Dog Club of America established the world's first open tumor registry for their breed. The GDC currently registers Bernese Mountain Dogs which have a positive diagnosis of histiocytosis or mastocytoma and enters tumors that have not yet been proven to be heritable in a research database. A research database is established when there is a question of diagnosis or mode of inheritance.
At the AKC Molecular Genetics and Canine Genetics Health Conference in 1994, there were 30 podium presentations. Most speakers at some point in their presentation stressed the absolute need to share data in an open manner. Some stressed the need for an open genetic disease data bank.
What You Should Know About the GDC and Open Versus Closed (or Confidential) Registries
An open genetic disease registry is a data bank of genetic history for any breed and for specific genetic diseases; and in fact, under the GDC charter, such data could be gathered for any species with known genetic diseases. In an open registry, owners, breeders, veterinarians, and scientists can trace the genetic history of any particular dog once that dog and close relatives have been registered. If we are going to improve breeds and control genetic diseases, the incidence of the disease within the breed or a particular blood line must be known! This can only be done in an open registry with a large number of entries.
In the GDC open registry, information about each dog is automatically linked, by computer, with other relatives in the registry. In general, data in the GDC registry is available to people who need support and information which will lead to a reduction of genetic disease in a kennel or the breed. All information must be used in accordance with ethical breeding standards. All requests for information are maintained in our files.
This open registry delivers family information on specific animals to breeders ( for a nominal fee) in order for the breeder to make knowledgeable selection of mates whose bloodlines indicate a reduced risk of producing genetic disease. This information is available because the owner has signed a release in order for an individual to be placed in the open registry.
The GDC data will be invaluable to researchers who wish to look at the genetic makeup of families that have a high incidence of a specific genetic disease. This data will facilitate the collection of samples for DNA analysis within lines that show a high incidence of a disease.
This type of information is not available in a closed or confidential registry. It is only available when both normal and abnormal individuals are submitted to the registry in a manner that reduces bias, such as when conscientious breeders, in order to improve the health and well-being of their chosen breed, submit all information including litter registration, to an open registry regardless of the anticipated outcome.
A closed registry, on the other hand, gives only phenotypic information. It is only known that the individual is free of signs of the disease, but it is not known if the parents, siblings or half siblings are affected. It is well documented that the mating of phenotypic unaffected dogs may result in offspring that are affected, unaffected, or a combination of both. The converse is also true.
Registry with the GDC will give phenotypic data at one year of age for most orthopedic diseases. In late onset diseases such as progressive retinal atrophy (PRA) and sebaceous adenitis (SA) certification is yearly until the age of late onset is reached. The availability of genotypical data will depend upon the degree of participation by breeders, breed clubs and the dog-owning public. As GDC grows, more and more information will be available within a breed and specific families.
The following are examples of genetic diseases for which the GDC currently maintains open genetic registries. In the following inherited diseases, the age of onset is known and there is an accepted method of diagnosis: Hip Dysplasia; Elbow Dysplasia; Joint Incongruity; Fragmented Medial Coronoid Process; Ununited Anconeal Process; Osteochondrosis of the Medial Humeral Condyle; Osteochondrosis; Legg-Perthes; Craniomondibular Osteopathy; Medial Patellar Luxation; Sebaceous Adenitis. Also included are eye diseases which have been proven to be hereditary such as: Progressive Retinal Atrophy; Retinal Dysplasia; Corneal Dysplasia; Cataract; Pannus; Micropapilla; Tricuspid Valve Dysplasia in Labrador Retrievers.
In other diseases, there is a method of diagnosis but there is difficulty in differentiating between the hereditary and the idiopathic forms of the disease and the mode of inheritance has not been established. Some examples are: Diabetes Mellitus, Intervertebral Disc Disease and Hypothyroidism.
In these examples the answers may be found through the development of some acceptable means such as test mating or the establishment of a research database in the GDC registry. In a research database, information on both affected and unaffected individuals is placed in a data bank until sufficient data is collected to answer the questions of concern. When this is accomplished the research database will automatically be converted to an open registry.
Some examples of existing research databases which are currently maintained by the GDC include: Lateral Patellar Luxation (This is currently maintained for Great Pyrenees and Chinooks and all four varieties of Belgian Shepherds); Porto systemic shunts for all terrier breeds; Chondrodysplasia of Great Pyrenees; Tumors other than those proven to be hereditary in Bernese Mountain Dogs; and Idiopathic Epilepsy in Irish Setters and Labrador Retrievers.
Epilepsy is a disease that was identified in the recent AKC health survey as one of the major diseases of concern to many dog breeds. Unfortunately the mode of inheritance is unknown and there is no specific diagnostic test. With epilepsy, the establishment of a research database is essential. Until a definitive diagnostic test is developed, the diagnosis will depend upon veterinary evaluation. The veterinarian will need to rule out other causes of seizures and complete a form that will be evaluated by us to determine if the patient meets established criterion to be placed in the database for that breed.
Hereditary deafness is a major problem in the Dalmatian breed and in several other breeds as well. Currently there is a test to determine deafness, however, there is controversy on how the test should be administered. As soon as a panel of experts reach agreement on this point, an open registry will be established.
Some Common Questions To Consider
Why does the GDC register Hip and Elbow Dysplasia at one year of age and the OFA register the same diseases at two years of age?
Although the main question may be the evaluation of hips between the ages of one and two years, the more important consideration should be whether or not to use the GDC open registry since it will give genotypical information rather than only the phenotype of the dog in question.
The GDC was established based on the Swedish open registry which has a proven track record in reducing the incidence of hip dysplasia from 46% to 28% in five years using evaluation at one year of age. In all other countries the accepted age of evaluation is between 12 and 18 months. (The only organization that requires that certification wait until two years of age is the OFA.)
A reality of medicine is that all diagnostic tests (procedures) including radiographs have a degree of error which must be accepted. Indeed, variability of analysis due to different observers (inter-observer variation) is equal to the difference between the number of false normal examinations at 12 months of age; thus it is the human factor and not the age that keeps us from a higher level of competence. In order to compensate for inter-observer variation each film is read independently by two evaluators. If there is disagreement on any portion of the evaluation the study is interpreted by a third reader whose diagnosis establishes a majority opinion. In addition we request re-evaluation at a later date in any cases where there is broad disagreement and withhold certification until that time.
What impact will Canine Lemon Laws have?
Obviously this will depend upon the specific law but in general these laws place responsibility on the seller when a dog is found to be "defective." It appears that the legal test of responsibility will be whether or not the seller has used reasonable means to insure that the dog is normal. In the case of registered dogs it appears that the test will be whether or not the seller has used whatever means are available to ensure that the mating was one that could reasonably be expected to produce normal puppies. That is, breeding phenotypic normal dogs or through selection of a mate who had been evaluated by a registry or on the recommendation of a veterinarian. The following states are known to have puppy protection acts:
California, Florida and Maryland, and there may be others.
Who can certify eye examinations for the open registry?
Eyes can only be certified by a member of the American College of Veterinary Ophthalmology. It is best if a screening examination for open registry is requested on a "CERF" form. The owner's copy of that examination, or a copy of both sides of the owner's copy, is sent to the GDC with the GDC application form and a check for registration. When appropriate, the GDC issues a certificate of unaffected (valid for one year). An affected diagnosis is registered and the check is returned with the notice of registration.
Who procures the skin biopsies for the Sebaceous Adenitis registry?
The skin biopsy is done by any veterinarian in a manner described in the SA application form. The biopsy with the appropriate form and fees is then sent to one of the dermatopathologists listed on the back of the form.
Who procures the tissue biopsies or necropsy material for the tumor registry?
Biopsies are normally performed in the referring veterinarian's office. Anyone performing a biopsy or necropsy can send the appropriate samples, accompanied by the GDC tumor release form, to one of the pathologists listed on the form.
Is there any means of verification of accuracy?
Yes, an owner can request the GDC records on their dog(s) at any time in order to verify accuracy of that information.
In cases of disputed diagnosis, is there any recourse?
Yes, there is a protocol for appeal. Appeals are handled on an individual basis depending on the specific registry involved. There is no charge for an appeal.