This section contains chapters on 171 dog breeds, including all except the most recent of the AKC breeds at the date of publication. It should be recognized that all mixed-breed and purebred or purposely bred dogs carry detrimental genes and can be affected with genetic disorders. A generally accepted fallacy is that purebred dogs are affected with more genetic disease than mixed-breed dogs. For the most part, this is only true for the rarer breed-specific disorders. The most common canine genetic disorders occur across all breeds, and in practice, we see as much genetic disease in mixed-breed dogs as we do in purebred dogs. These include the most frequent canine genetic disorders reported by the AKC Canine Health Foundation: cancer, inherited eye disease, epilepsy, hip dysplasia, hypothyroidism, heart disease, autoimmune disease, allergies, patella luxation, and renal dysplasia.
There are defective genes that are old in the dog genome, and spread across all dogs regardless of ancestry. The development of pure breeds has compartmentalized genes into breed gene pools. Based on the genetic load of disease causing genes, each breed has different frequencies of common and uncommon genetic disorders. Some defective genes are ancient, and their existence preceded the differentiation of breeds. The autosomal recessive, progressive rod cone degeneration (prcd) form of progressive retinal atrophy (PRA), is caused by the exact same mutation in at least twenty-five different breeds. Other defective mutations occurred more recently, and by propagation through foundation dogs or popular sires, have developed into breed specific genetic disorders.
A recent development in dog breeding is the rise of designer breeds - dogs produced through the purposeful crossbreeding of two different pure breeds. These are not considered specific breeds; because they do not breed true to reproduce themselves if bred together. It is only the original cross, which produces them as the F1 (first filial) generation. There is a general expectation that designer dogs should be healthier, simply because they are crossbred. However, due to the presence of disease liability genes across all breeds, this is not the case. The only way to have a realistic expectation that any purposely bred dog - purebred or crossbred - is going to be healthy is if the breeder is actively testing and screening breeding stock for genetic disease. The purebred parents of designer dogs should be screened for their respective breed-specific screening tests. Prospective owners should ask to see test results on the parents of dogs for sale. Many of these test results are available to the public in online registries from the OFA (Orthopedic Foundation for Animals: www.offa.org), CHIC (Canine Health Information Center: www.caninehealthinfo.org), and CERF (Canine Eye Registry Foundation: www.vmdb.org/cerf.html).
Medical conditions listed in the breed chapters are grouped under the following headers; Inherited Diseases (those with a defined mode of inheritance), and Disease Predispositions (those where a mode of inheritance is not defined). Many texts that report breed related genetic disease do not state the relative frequency of the disorders within the breed. In many instances, a “breed-related disorder” is reported due to a single published case report for a disease in the breed. In this section, the inherited diseases and breed predispositions are ordered based on their perceived incidence in the breed. Reported frequencies are stated based on genetic testing services, published articles, and health surveys. This process is the same as comparing apples to oranges; as the methods, populations, and statistics of each report cannot be adequately compared to each other. However, the disorders are ordered with the most common first, and least common last based on the author’s experience.
Recommendations for genetic testing of breeding dogs are based on the breed-specific recommendations of the US parent club through the CHIC program. Where there are additional tests suggested beyond the CHIC recommendations, they are also listed. In all dog breeds, genetic testing of breeding stock for the major common inherited diseases is recommended. These include hip and elbow radiographs for dysplasia (or Legg-Calve-Perthes disease), a CERF eye examination by a board certified veterinary ophthalmologist, a thyroid profile including thyroglobulin autoantibodies, a cardiac evaluation, and a patella evaluation. Most of these are once-in-a-lifetime tests. It is not ethical to breed dogs (either purebred, designer-bred, or purposely bred) without ensuring that both parents are free of testable genetic disease.
Not every dog breed is included in the first edition, and some breed-related disorders may be missing, because there was no published reference at the time of publication. As the website is updated, adjustments and additions will need to be made in order to keep the listings current. Readers are encouraged to send comments to help us update the dog breed section. Use the contact address provided in the website preface. Chapters are in alphabetical order.
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