Genetic testing became a reality for Border Collies more than 50 years after McCulloch's book was written. He surely would appreciate what this means to today's breeder. A defined, inherited disease can be avoided and the breed can benefit immediately upon use of genetic testing. In 2005 a DNA based test for Collie Eye Anomaly (CEA) was offered worldwide by OptiGen, a private company in the United States. This test followed on years of observation and research, funded in part by the ABCA-American Border Collie Association, along with participation by other concerned groups and individuals. Eye anomaly of the collie was described in Europe in the 1960's. In the 1980's, Dr. Peter Bedford carefully tracked the incidence of Collie Eye Anomaly in sheepdogo breeds in the UK. The disease clearly was prevalent and of serious concern. The primary problem in underdevelopment of the eye tissue layer called the choroid. The choroid appears pale and thin and blood vessels of the choroid can easily be recognized in those ''thin'' areas. In mildly affected dogs, choroidal thinning is the only detectable abnormality and the dog retains normal vision throughout life. However, dogs with mild disase can have severly affected offspring. Approximately 25% of dogs with CEA are severely affected. A smaller fraction will have colobomas, retinal detachment and/or bleeding inside the eye. Complications of severe disease can lead to vision loss, although rarely threatens total blindness. The only approach for breeders had been selective breeding to derease the prevalence and severity of the disease. This was only partially successful, since the CEA recessive mutation was essentially ''hidden'' in mildly affected dogs. By mid-1990, Border Collie breeders in the United States, alarmed with a high rate of eye disease thought to be Progressive Retinal Atrophy (PRA), consulted Dr. Greg Acland at Cornell University. Upon examining hundreds at national trials, Aclad found almost 3% of the US Border Collies were affected with CEA, but very few with PRA. Clearly CEA was the disease of greatest concern. Acland produced research CEA pedigrees and in collaboration with other research groups, applied modern gene mapping technology to locate the gene and define the precise genetic cause-mutation-for the disease. A commercial test was develeoped to identify dogs that are genetically affected or carriers of the CEA mutation. Cooperation between Cornell Research Foundation, INC and the Fred Hutchinson Cancer Research Center allowed license of the test to Optigen.
The CEA genetic test is important to all breeding plans. At this writing, the CEA mutation is distributed uniformly worldwide with 28% of Border Collies being carriers and 2% being affected. Due to wide variation of severity of CEA, the DNA based test adds crucial information to routine eye examinations for identifying affected dogs. Implementation of breed club recommendations will probably reduce the mutation frequency over time. Meanwhile, with a DNA test, no affected dogs need be produced.
There are other genetic tests for sheepdog disease (for example, Neuronal Ceroid Lipofucinosis, Ivermectin sensitivity, Gray Collie Syndrome) and for other breeds (especially those with PRA). Researchers will develop more tests for important diseases as their work and your support continue. Luckily, genetic news can be shared with you much faster now than 50 years ago.
Jeanette S. Felix, PH.D. President, OptiGen, LLC
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