COLLIE EYE ANOMALYA defect that we see quite often is chorioretinal dysplasia (CRD). Little areas of the retina are not developed well. Vision is not affected. An other common disorder is Coloboma (Col.) It's a closing defect of the optic disc. Most Coloboma's cause no recognizable defect in vision. There are also more serious types of CEA like retinal detachments and intraocular haemorrhage, but these defects are less common. CEA is supposedly caused by a autosomal recessive gene, this means that the condition is not color- or sex-linked and a dog has to have received the CEA gene from both parents if he is affected. It's also possible that a dog has only got one gene from one of his parents. The dog has no symptoms of CEA. This non-affected dog is though a "carrier". Puppies has to be examined between the six and eight weeks by a qualified eye specialist. The young age is because the back of the eye has not yet developed the reflective layer which can mask some defects. The Dutch Sheltie Club recommends to breed only with non-affected Shelties. To select against this condition all born puppies must be checked before they are 8 weeks old because if one pup is affected both parents must carry one gene for CEA. Only this way we can find out which dogs are non-affected, affected or carriers, in other words: how big the CEA-problem is in our breed. Karin M. Vrieswijk-Zeijlemaker |
