Professor Peter Bedford
B.Vetmed, PhD, DVO phthal, DipEC

Writes for the Association on the primary health issue concerning Glens

Progressive Retinal Atrophy ( PRA ) is perhaps the most well known of the inherited eye diseases that are seen in pedigree dogs.  Sadly it is just one of many severe defects that occur, but it is known so well because it always causes blindness.  In fact there are several retinal degenerations which are all called PRA, some occurring early in life and result from actual congenital defects whilst other do not occur until middle age.  Most are inherited as single gene defects and sadly the normal dogs related to afflicted dogs are often carriers of the genetic defect required to produce the disease.  Sadly - and I keep using this word - the Glen has PRA and in the absence of the appropriate DNA based test, disease control will be very difficult.

Your gene pool is small and selecting away from the affected lines means you have to avoid using carrier stock.  Sadly (again) the ophthalmoscope cannot the detect the carrier animal, and it has always been difficult to avoid using quality animals with normal eyes which are related to affected animals.  However you must always bear in mind that PRA is a breed problem, not just individuals.  As such, disease control must be preached as a breed activity.  Of course, the presence of a DNA based test would mean that affecteds and carriers can be used in your breeding programmes. 
Professor Peter Bedford B.Vetmed, PhD, DVO phthal, DipEC