In August 2012, the Laboklin Laboratory announced that it would no longer be offering the Cord1 PRA DNA test, other than for research purposes. Its decision was based on a study of early onset PRA in Cord1 genetically Affected Dachshunds, which was carried out by researchers at the University of Pennsylvania and published in July 2012. Immediately following the Laboklin announcement, the ESS Health Co-ordinators contacted the Animal Health Trust for clarification of the findings of this study and whether there were any implications which might alter the advice that should be offered to ESS breeders and owners.

Dr. Cathryn Mellersh of The Animal Health Trust and Dr. David Sargan of Cambridge University issued a statement in August 2012, which can be read in full here. The situation can be summarised as follows:

  • The research study only investigated early onset PRA in Dachshunds, so strictly speaking the conclusions related only to Dachshunds, although it could be assumed that a similar situation applies in ESSs. (The major stumbling block with research specifically using ESSs is the serious lack of suitable samples.)
  • The study adds nothing to what has been known since 2009, which is that there is almost certainly a second (as yet unidentified), modifying gene mutation that needs to be present for the development of early onset PRA in Cord1 genetically Affected dogs. Without this second mutation, Cord1 PRA is more likely to be late onset.
  • Although some dogs without the second modifying gene may never clinically develop Cord1 PRA during their lifetimes, some of them will. AHT research using ERG (electroretinography) testing showed that Cord1 genetically Affected dogs that were thought to be clinically normal, do indeed have reduced retinal function which can’t be detected when using the standard clinical eye test.
  • In Dachshunds, although the second mutation hasn’t yet been precisely identified, they do know in which region of the genome it lies, and we await news of any further developments on that front.
    • The clear advice from the AHT was that the Cord1 DNA test for ESSs remains valid and valuable, and that Affected and Carrier dogs should only be mated to Clear dogs. A decision was made not to issue a statement to ESS owners last August, as the advice on using the ESS Cord1 PRA DNA test has not changed. However, as this issue has recently been highlighted on various ESS internet discussion forums, it is hoped this statement will help clarify the situation for everyone.

      The Cord1 PRA DNA test is available from the Animal Health Trust and remains an ESS requirement under the KC Assured Breeder Scheme.

      Louise Scott & Lesley Bloomfield
      UK English Springer Spaniel Clubs Joint Health Co-ordinators

      1st March 2013

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