Optigen :   DNA - test on J175

Optigen has undertaken a DNA study of the Swedish Vallhund regarding the eye anomalies found in some eye exams, in particular dogs in Finland and a couple of Australian dogs.

Optigen has looked at eye exams of and pedigrees of dogs that had a J175 exam and two Australian dogs with an indication of Tapetal Mottling on the Findus. Optigen then request blood samples of 10 dogs for an initial DNA study, 9 of these dogs resided in Finland and the other was an Australian dog. These samples were sent January 2006 of which Optigen have been undertaking DNA testing to determine what possible problems the breed may have.

 The DNA test has revealed that 6 of the 10 dogs do have PRA. Now the problem that Optigen has encountered and hence the reason for information not being released is:

1. The dogs concerned have not been identified

2. Optigen does not know what form of PRA the breed has. They can confirm hat the breed does not have the common form of PRA being PRCD.

Optigen is continuing their testing of the blood samples in an attempt to identify the breeds PRA type. This could well mean that the PRA found in the Swedish Vallhund is a new form of PRA. Until the PRA type can be identified determinations can not be made as to how this form of PRA is inherited and what solutions there are to breeders regarding the breed's gene pool. 

Breeders should be regularly eye testing and gaining as much information as possible regarding their breeding stock.

The problem with eye exams is they do not identify any carriers only affected dogs. Once Optigen have come to a determination regarding the breeds form of PRA and its inheritability, hopefully a blood test will be available for breeders to use that will indicate, affected, carriers and clear for PRA.

Any eye exam that finds an anomaly in both eyes should be of concern to the breeder and the examiner. PRA is not isolated to one eye it is in both eyes. To date only a few dogs have some loss of vision and are now over 10 years of age. Although too early to say but it does seem to appear that the PRA found in this breed to date seems to form at a later age than other breeds that have PRA, now in saying this it does not mean that this will remain this way.  

Attempts to eradicate heritable disease should not be pursued to the detriment of the breed. We need to know what we are actually dealing with; there are those who will urge that, not only should affected animals be withdrawn from breeding (as soon as the condition is identified) but also their progeny who are immediately identified as carriers (if not affected).

Rigorous culling has the potential to destroy what is good while attempting to control what is bad. In genetic terms, it may have the effect of eliminating a large bank of valuable genetic material that can never be recovered. There are few pure bred dog populations in any country that can afford large scale loss to the genetic pool.

Modified out of the orinal letter by Leonie Darling