Collie eye anomaly in the United Kingdom.

Approximately 2500 rough collies, smooth collies and Shetland sheepdogs were examined during a three year period in an attempt to establish the incidence of collie eye anomaly in the United Kingdom and to produce data on the hereditability of the disease. The overall incidence in the two collie breeds was approximately 64 per cent, but the disease was seen with slightly more frequency in the Shetland sheepdog, 72 per cent of the dogs examined being affected. Pedigree analysis and test mating has confirmed the opinion held in the USA that the disease is inherited as an autosomal recessive trait. In this report the pleomorphism of the disease in these three breeds is discussed together with the inherent problems in diagnosis.