Congenital stationary night blindness / CSNB (LRIT3-related) - Beagle

What does this test examine?

This genetic test analyses the LRIT3 variant c.762_763delG in the Beagle. The disorder is also described as Congenital Stationary Night Blindness, CSNB, complete CSNB and LRIT3-related night blindness.

What does CSNB mean for the dog?

CSNB is an inherited retinal disorder in which vision in low light is especially impaired. Affected Beagles can function relatively well in daylight, but have difficulty orienting, avoiding obstacles or moving confidently in twilight or darkness. The stationary nature means that the condition is not typically expected to show progressive worsening.

LRIT3 is important for retinal signal transmission between photoreceptors and ON bipolar cells. This mainly disrupts processing of light signals at low light intensity. For owners, the result can explain why a dog appears normal during the day but becomes hesitant or cautious in the evening or in dark rooms.

Inheritance and result

CSNB in Beagles is inherited as an autosomal recessive trait. Carriers with one copy remain clear of this form but can pass the variant on. Dogs with two copies develop the disorder. Testing breeding dogs allows carriers to be used responsibly with clear-tested partners.

Practical value of this test

• Helps Beagle breeders identify carriers and avoid risk matings.
• Allows healthy carriers to remain in the population through matings with clear-tested partners.
• Provides clear context when a dog is insecure in the dark or has abnormal eye or ERG findings.
• Supports transparent communication with puppy buyers about inherited eye disease in the line.
• Distinguishes LRIT3-related CSNB from other causes of poor vision or night blindness.