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prcd-PRA Test

 For: Entlebucher Mountain Dog

Reliable identification of dogs that do not carry disease genes is the key to eliminating inherited recessive diseases, like prcd-PRA. The OptiGen prcd test for Entlebucher Mountain Dogs provides almost 100% identification of these dogs. Called "genetically clear", "noncarriers" or, more formally, "homozygous normals," such dogs pass the normal gene on to all their pups with a very high probability - which means that their pups have a very low risk of being affected with prcd. These "clear" dogs can be bred to any mate - even to a prcd-affected dog that may be a desirable breeding prospect for other reasons.


Homozygous means both copies of the gene in your dog are the SAME - both normal or both prcd. A carrier has one normal and one prcd gene.

The OptiGen prcd test is done on a small sample of blood from the dog. The test analyzes the specific DNA mutation causing prcd-PRA. The OptiGen test detects the mutant, abnormal gene copy and the normal gene copy. The result of the test is a genotype and allows separation of dogs into three groups: Normal/Clear (homozygous normal), Carrier (heterozygous) and Affected (homozygous mutant).

Possible results using the OptiGen prcd test for Entlebucher Mountain Dogs


Risk Group

Significance For Breeding

Risk of prcd Disease

Homozygous Normal Normal/Clear Can be bred to any dog, extremely low risk of producing affecteds Extremely Low


Should be bred only to Normal/Clear to remove risk of producing affecteds Extremely Low
Homozygous Mutant


Should be bred only to Normal/Clear to remove risk of producing affecteds Very High

Questions and Answers:

  1. Is there more than one type of PRA in Entlebucher Mountain Dogs?
    The only known form of inherited PRA in Entlebucher Mountain Dogs is prcd-PRA. Other retinal diseases can be confused with prcd-PRA. For example, multi-focal retinopathy is a non-inherited disease seen in this breed. Multi-focal retinopathy is usually asymmetric (different symptoms in each eye), shows foci of what appears to be healed inflammation, and can cause a generalized retinal atrophy. Also, cases of acquired retinal disease due to various non-genetic causes like trauma, active work, etc., can be confused with PRA. The OptiGen prcd-PRA test will accurately distinguish dogs with acquired disease or multi-focal retinopathy from truly prcd-PRA affected dogs.

  2. What is the usual age at diagnosis?
    Entlebucher Mountain Dogs are typically diagnosed with prcd-PRA around 3-6 years of age. As more dogs are examined, it’s likely that even younger and older dogs will be discovered showing first signs of prcd-PRA. According to the experience of the National Entlebucher Mountain Dog Association (NEMDA), most PRA-affected dogs will become totally blind by age 6-8 years. However, the progression of PRA in this breed can be quite slow, sometimes allowing some useful vision even late in life.

  3. How frequent is PRA in Entlebucher Mountain Dogs?
    The best estimate at present for the frequency of PRA in Entlebucher Mountain Dogs is discussed on the
    NEMDA website under "Breed Health." There it reports that, based on ophthalmologic examinations of 276 Entlebuchers between 1987-1992: "A progressive retinal degeneration was observed in 24.9% of the dogs examined." It also cautions: "There are NO known clear lines of the Entlebucher breed for PRA." An updated frequency estimate will be achieved when a large set of Entlebuchers from many lines is tested with this new genetic test.

  4. Are there any proven cases of false negative in this test?
    So far, there are no cases of false negatives in the test used on Entlebucher Mountain Dogs. However, as larger numbers of dogs are tested, it is possible that such a case will be identified. It is also possible that a few will be discovered with a retinal disease that is not genetic prcd-PRA. They might have another, rare form of PRA or an acquired retinal degenerative disorder. OptiGen will follow-up on any Entlebucher Mountain Dog that is diagnosed with some type of PRA but does not test as Affected. Please refer to the paragraph "Benefits and Limits to All Genetic Testing" on the prcd-PRA general information page.

  5. Are there any proven cases of false positive in this test similar to other breeds?
    So far there is no known case of a false positive in Entlebucher Mountain Dogs. That means - we have not yet seen a Carrier dog that might actually be Normal/Clear, nor an Affected dog that might actually be Carrier or even Normal/Clear. This situation is very different than the initial prcd-PRA test in other breeds, in which the rate of false positives was substantial.

  6. Should carrier or affected dogs be bred?
    OptiGen test results should be used in a responsible breeding program. The genetic status of each breeding dog should be known. Carrier and affected dogs with other desirable traits can be bred safely, but only to a genetically Normal/Clear dog in order to prevent prcd-PRA disease. There is no logical reason to eliminate Carrier or Affected dogs from a breeding program, if they are valued dogs. Please review "Breeding Strategies" at the page "prcd-PRA Test - General Information."

  7. What Entlebucher Mountain Dogs were used in the research to develop their specific prcd-PRA test?
    DNA from over 50 Entlebuchers, most of them owned in North America, was studied to develop and validate this test at the research laboratory, Cornell University. Extensive analysis proved that the known cases of PRA in this breed are caused by the prcd gene. To the best of our knowledge, the OptiGen test can be used on purebred, registered Entlebucher Mountain Dogs worldwide. OptiGen will continue to test PRA-affected dogs at no charge, provided an eye exam report and pedigree are reviewed in advance of submitting the sample.

  8. Who funded the research leading to this test?
    Financial support for this research conducted in the laboratories of Drs. Gregory Acland and Gustavo Aguirre at The James A. Baker Institute, Cornell University, was provided by The Morris Animal Foundation/The Seeing Eye, Inc., The National Institutes of Health, and The Foundation Fighting Blindness. OptiGen, LLC, collaborated with screening and final refinements for a commercial test.

  9. Why is the Entlebucher Mountain Dog PRA test restricted by patent and license rights?
    Universities routinely review research discoveries made by their faculty and staff for commercial value. When appropriate, the discovery is patented and use of the patent is licensed for business purposes. Cornell Research Foundation, Inc. owns the patent for all DNA-based genetic tests for prcd-PRA. (1998 - prcd-PRA US Patent No. 5,804,388; prcd-PRA Canadian Patent No. CA2306194; prcd-PRA U.K. Patent No. 2 341 926) Since 1998, OptiGen, LLC, has had an exclusive license arrangement with Cornell Research Foundation to commercialize the test.

  10. What determines the price of a genetic test?
    The price applied to a test reflects the entire cost of performing the test, including laboratory, office and administrative staff inputs and materials used, and the infrastructure to ensure quality control, reliability and stability of the business. The price also includes a portion for obligatory royalty payments to Cornell Research Foundation, Inc. and to Roche Molecular Systems, Inc. for use of PCR technology. OptiGen’s price range for various tests is $80 to $195 per test.

  11. Can any other laboratory offer this test?
    Under the lawful protections of the patents and exclusive license, no other North American or United Kingdom laboratory may offer a test for prcd-PRA in any breed.

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Tel: 607 257 0301 · Fax: 607 257 0353 · email: or
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