-Progressive Retinal Atrophy (prcd-PRA)-

Progressive Retinal Atrophy, or PRA, is an inherited eye disease in which the light-sensitive cells in the retina gradually deteriorate. This condition progresses slowly but inevitably and, unfortunately, always leads to blindness in affected dogs.

One specific form, known as prcd-PRA, occurs in English Cocker Spaniels and usually begins at a young age. The first cells to be affected are the rods, which are responsible for vision in low light. As a result, night blindness is typically the first sign. As the disease progresses, the cone cells—needed for daylight and color vision—are also destroyed, leading to complete loss of sight.

Currently, there is no treatment available for prcd-PRA. This makes preventive genetic testing all the more important, as it is the only way to ensure the disease is not passed on to future generations.

Inheritance: How prcd-PRA is Passed On

prcd-PRA follows an autosomal recessive inheritance pattern.

This means:

Only dogs that inherit two copies of the mutated gene, one from each parent, will develop the disease.
Dogs that carry only one copy of the mutation (carriers) do not become ill themselves, but they can pass the mutation on to their offspring.

If two carriers are bred, there is a 25 percent chance that a puppy will inherit both copies of the mutated gene and eventually go blind.

Genotypes at a Glance

Genotyp	Bedeutung	Gesundheitsstatus	Zuchteinsatz
N/N (frei / clear / Optigen A)	The dog does not carry a defective gene	Will not develop the disease	Unrestricted breeding
N/PRA (Träger / carrier / Optigen B)	The dog carries a defective gene.	Unaffected but carries a 50% risk of inheritance	Mate only with a clear/unaffected partner
PRA/PRA (betroffen / affected / Optigen C)	The dog carries two defective genes.	Very high risk of becoming ill.	Not recommended for breeding, except when paired with a healthy partner (offspring will be homozygous carriers).

Verpaarungstabellen – was kommt dabei heraus?

Vater	Mutter	Nachkommen
A (clear)	A (clear)	100 % A (clear)
A (clear)	B (carrier)	50 % A, 50 % B
A (clear)	C (affected)	100 % B
B (carrier)	B (carrier)	25 % A, 50 % B, 25 % C
B (carrier)	C (affected)	50 % B, 50 % C
C (affected)	C (affected)	100 % C (affected)

Wichtig: Durch sorgfältige Gentests kann prcd-PRA vollständig aus der Zucht ausgeschlossen werden – ohne gesunde Trägertiere direkt aus der Zucht zu nehmen. Das hilft, den Genpool breit und gesund zu halten.

Ein Hinweis zum Schluss
Ein Hund, der frei von prcd-PRA ist, wird nicht an dieser Form der PRA erkranken.
Das bedeutet jedoch nicht, dass er generell vor Augenerkrankungen sicher ist. Es gibt weitere Formen der PRA oder andere Augenkrankheiten wie Katarakt (grauer Star), die genetisch unabhängig sind.

Daher ist regelmäßige tierärztliche Augenuntersuchung (z. B. DOK/EVCO) zusätzlich zum Gentest empfehlenswert – für einen klaren Blick ins Leben!