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Written by
Dr. Andrew Turner
Veterinary Eye Specialist |
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Collie Eye Anomaly (CEA), a hidden cause of blindness, is a
recessively inherited congenital defect in which we see pale
areas at the back of the eye (called choroidal hypoplasia).
Increased tortuosity of retinal blood vessels (colobomas) in the
optic nerve head and occasional retinal haemorrhage and
detachment. Not all CEA positive dogs show ALL these signs. |
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HEREDITY |
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It is a misconception to assume breeding mildly affected dogs
will produce normal offspring – if the condition is present
clinically, the dog is carrying the gene(s) for CEA. |
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INCIDENCE |
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Border collies show an incidence of less than 10%. Rough and Smooth Collies have a reported incidence of 50-90%. One survey from Queensland found an incidence in Shelties of approximately 74%. Similarly the incidence is high in the rest of Australia. |
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LOSS OF VISION |
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Poor vision is often difficult to detect especially if the CEA signs are mild. Owners report poor vision especially with large pits in the optic nerve head. Vision loss may occur if there is retinal haemorrhage and detachment. |
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THE YOUNG PUP |
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Pups purchased for breeding purposes should be checked by a
veterinary eye specialist at approximately 6 – 8 weeks of age.
This is the best time to check for choroidal hypoplasia.
Colobomas are checked later at around 14 weeks of age or later.
CEA is easiest to detect in young pups. After 14 weeks of age it is not possible to detect all cases of CEA. The development of retinal pigment can cover the signs of CEA. While the dog can appear normal (hence the term “go normal”), it can still transmit the CEA gene(s). |
| DETECTION OF CARRIERS BY TEST MATING |
| Most dogs with normal eyes are carriers. Test mating detects carriers, slightly affected dogs and ‘go normals’. Test mating is the most efficient method of reducing the incidence of CEA. Mating clinically unaffected dogs will ultimately reduce the incidence of CEA in all types of Collies although not as rapidly as test mating. |
| REDUCING COLLIE EYE ANOMALY IN YOUR KENNEL |
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In the ideal situation it would be best to discard all affected
dogs, their parents and progeny from your breeding program. In
the Border Collie, the incidence is now low enough that it may
not be wise to breed from any dog that is a known carrier. Breeding from mildly affected dogs will NOT reduce the incidence of CEA but may reduce the severity of the condition in the progeny. Test mate to detect carriers and ‘go normals’. Note that mating an affected dog to a genetically clear dog will produce a litter of carriers. Buy or breed only from dogs certified free of CEA by a veterinary eye specialist. |
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Dr. Turner can be contacted at: |
