What is CEA?

What is PRA?

Eye examination

Collie Eye Anomaly (CEA) is an eyedisease that was first discovered in the 1950s and that got its name after the breed where it was first found. CEA is frequently occuring in Collies and Shelties in Sweden and other countries, and is also known in other breeds.

Several various partsymptoms is a part of CEA. They are divided into primary and secondary. Primary symptoms are CRD (ChorioRetinal Dysplasia) and coloboma. Secondary (complication-) symptoms are bleeding and/or detachment of the retina.

CRD is a malformation in the choroidea and in the retina.The diagnose CRD is easiest made when examining the eyes of young puppies. An examination before 8-10 weeks of age will tell if the dog has got CRD or not. The change is more visible the younger the pup is. Later the change can be concealed behind the glittering layer that makes the dogs eyes shimmer in the dark. CRD is not considered to affect eyevision.

Coloboma is a hole in or beside the optic nerve. It will come up during the eyes early growth. The size may vary both sideways and at depth. A large coloboma can form a hernia the size of a pea on the eye. When examining small puppies you will often, but not always, be able to discover coloboma. The optic nerve can change its looks during growth, both to the worse and to the better. That is why at least breeding dogs are recommended an exam as adults before their first mating.

Coloboma is considered to cause bleeding and/or detachment of the retina. A minor detachment can go back and normalize. Overall detachment of the retina and severe bleeding will cause blindness.

CEA is hereditary. Earlier, CEA was considered to follow a simple autosomal inheritance, but a research made by myself, Nils Wallin Håkansson and Åke Hedhammar, is indicating that a polygenic inherity is more likely. We also found that the number of puppies in a litter is affected if a parent has coloboma. The average in a litter is dropping from 5 to 4 puppies in the Collie breed.

Recommendation: All puppies should get an examination concerning CEA before delivery, at 10 weeks of age the latest. Breeding dogs shall also be examined for CEA as adults. Dogs with coloboma should not be used in breeding. Dogs with CRD are satisfactory as pets but CRD is affecting the breeding value negatively.

Berit Wallin Håkanson

Opthomal veterinary at the Region Animal hospital of Strömsholm