May 2013
Cone Degeneration causes day blindness; affected dogs can’t see in bright light but have normal vision when the light level is low. CD can be diagnosed between 8 and 12 weeks of age. The mutation appears to be recessive. Carriers of one copy should be bred only to mates that have tested clear for CD. Those which are diagnosed affected or which have two copies of the mutation should not be bred. There is a DNA test available.