The collie eye anomaly : a simple recessive mode of inheritance?
Camann, Christine Tecklenburg
The Collie Eye Anomaly is a congenital disorder which is equally prevalent in males and females, and among all normal coat colors of Collie dogs. Since it was first described in 1953, many estimates have been made of its prevalence, ranging from 60% to over 90%. From 1975 to June 1979 the Canine Eye Registration Foundation, Inc. (CERF) functioned as a registry for the listing of purebred dogs susceptible to hereditary eye diseases which had been examined by approved veterinary ophthalmologists and found to be free of such disease. During this period CERF received reports on examinations of a total of 17,302 Collies. Of these, 12,465 (72%) were classificed as affected. The anomaly consists of a wide range of ocular abnormalities. When severe lesions are present, the affected animal suffers from blindness, but in milder cases, which are by far more common, there are often no outward symptoms. Although Collie Eye is bilaterally expressed, it is usually not symmetrical; an individual may be mildly affected in one eye and severely affected in the other eye. Unlike many other congenital eye diseases, the Collie Eye Anomaly is generally non-progressive. Occasionally, retinal detachment may occur later in life, but usually an affected animal's vision does not worsen with age. Presently, the Collie Eye Anomaly is thought by most people to be due to the presence of a simple autosomal recessive gene; affected animals are presumed to be homozygous for this gene. Because the anomaly has such a high prevalence in the breed, it is assumed that most phenotypically normal-eyed dogs are actually genotypically heterozygous.
Senior seminar paperSeminar SF610.1 1980 no.8005
Dogs -- Abnormalities