The results of eye examinations of 741 rough collies for collie eye anomaly (CEA) are described. Of the examined dogs, 40-8 per cent had CEA, including, in most cases, chorioretinal dysplasia (CRD). 7-7 per cent had coloboma of the optic disc while 3–5 per cent had complications of CEA, either retinal detachment or intraocular bleeding. There was no sex difference nor was the frequency of the disease influenced by coat colour. After estimating the total frequencies of the different manifestations of the disease, the dogs were divided into two groups according to the age at first examination. In the group of dogs examined between seven weeks and three months old, 48-9 per cent had CEA, compared to a frequency of 25-6 per cent in the group of dogs examined after three months of age.
All the puppies with coloboma also showed signs of CRD, while among the older dogs 11 of the 66 CEA cases reported showed signs of coloboma without CRD.
Twenty-two dogs which had been examined as puppies and given the diagnosis CEA with minor chorioretinal changes were re-examined at an older age. Of these dogs, 15 had ophthalmoscopi-cally normal fundi at re-examination while seven were unchanged from the first examination.