CEA - COLLIE EYE ANOMALY
CLINICAL NAME - CHOROIDAL HYPOPLASIA
CEA/CH causes abnormal development of the choroid - an important layer of tissue under the retina of the eye. Since the choroid layer does not develop normally from the start, the primary abnormality can be diagnosed at a very young age.
The clinical effects vary greatly among affected dogs within one breed, between parent and offspring and even within a litter. Most often the disease presents as a mild form in affected dogs and the presence of the disease can only be detected upon ophthalmologic examination; the dog retains normal vision throughout life, however, dogs with mild disease can produce severely affected offspring.
The severe (thankfully rare) form of the disease presents with related problems with the health of the eye (such as retinal detachment and intraocular haemorhage) that can result in serious vision loss in some cases.
If your dog is mildly affected, the best way to explain CEA is that if he were a human, he may have to wear glasses in later life but the majority of collies with mild CEA show no apparent visual defect. .
The disease is described as an autosomal recessive condition. This means that a dog must inherit two copies of an abnormal gene (one from its mother and one from its father) before its health is affected. A dog that inherits only one copy of the abnormal gene (from its mother or its father) will have no signs of the disease, but will be a carrier and may pass the gene on to any offspring.
It is possible for litters to be tested for congenital hereditary conditions such as Collie Eye Anomaly and Multifocal Retinal Dysplasia when they are 5 to 12 weeks old. Testing over this age may show a 'false negative' as the fundus of the eye colours with age and the lesion may no longer be visible. This does not mean that it is not there and so a dog can be clinically clear but still be genetically affected.
Please click here for an extended article by specialist Dr Sheila Crispin regarding Hereditary Eye Diseases in dogs.
To find you nearest eye panelist to assess your litter/older dog please use this link to the BVA.