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Health > Eyes > Collie Eye Anomaly (CEA)

It is an inherited disorder of the choroid structure of the eye. This disease is seen most frequently in U.S. collies, but also worldwide in Australian Shepherds, Border Collies,  Lancashire Heelers, and Shetland Sheepdogs.

It is also known as:

Since the choroid layer does not develop normally from the start, the primary abnormality can be diagnosed at a very young age typically between 5 - 12 weeks.

Symptoms and signs – the clinical phenotype – can vary greatly among affected dogs within one breed, between parent and offspring and even within a litter. This creates a difficult situation for the breeder. Learning about the genetic cause and the course of the disease will help you understand how to manage it better and eventually avoid it altogether with genetic testing.

Cure: None

The primary problem is choroidal hypoplasia (CH). There is under-development (hypoplasia) of the eye tissue layer called the choroid. The choroid appears pale and thin, almost transparent, and the blood vessels of the choroid can easily be recognized in those "thin" areas. The ophthalmologist, looking at the back of the eye (the fundus) with an ophthalmoscope, typically will see an area of choroidal thinning that appears like a "window" to the underlying vessels and sclera.

MILD disease: Mild disease is very common in U.S. collies and is present in the other breeds named above. It is easily recognizable on careful ophthalmologic examination as early as 5 to 8 weeks of age. The lesion appears as an area lateral (temporal) to the optic disc with reduction or absence of pigment so that the underlying vessels of the choroid are seen. The choroidal vessels may be reduced in number and of abnormal shape. The underlying white sclera might also be visible. Once the retina changes to its adult color around 3 months of age, the normal pigment sometimes masks the changes in the choroid (so-called "go normal" – read more below). In mildly affected dogs, choroidal thinning is the only detectable abnormality and the dog retains normal vision throughout life. However, dogs with mild disease can produce severely affected offspring.

(The eye anomaly merle can be confused with choroidal hypoplasia, primarily in dogs from merle to merle breeding and whose coat color is whiter than their littermates. Although both conditions are inherited, can occur in the same breed and exhibit a range of fundus anomalies, there are sufficient dissimilarities for the ophthalmologist to make the distinction.)

SEVERE disease: In severely affected dogs, approximately 25% of dogs with CEA/CH, there are related problems with the health of the eye that can result in serious vision loss in some cases. Colobomas are seen at and near the optic nerve head as outpouchings or “pits” in the eye tissue layers. Colobomas can lead to secondary complications such as partial or complete retinal detachments and/or growth of new but abnormal blood vessels with hemorrhage – bleeding inside the eye. This happens in 5-10% of dogs with CEA/CH, generally by 2 years of age, and can affect either one or both eyes. Complications of severe disease can lead to vision loss, although this disorder only rarely threatens total blindness.

CEA/CH is not progressive in the usual sense. The essential features, choroidal hypoplasia and coloboma, are congenital – the abnormalities develop as the eye develops. These features are also stationary once ocular development is complete around 8-12 weeks of life. Retinal detachments and/or aberrant vessel formation can be congenital or develop later, in general only in eyes with colobomas.

Expected Results of Breeding Strategies for Inherited Recessive Diseases
Parent 1
Genotype
Parent 2     Genotype
Normal Carrier Affected
Normal All = Normal 1/2 = Normal
1/2 = Carriers
All = Carriers
Carrier 1/2 = Normal
1/2 = Carriers
1/4 = Normal
1/2 = Carriers
1/4 = Affected
1/2 = Carriers
1/2 = Affected
Affected All = Carriers 1/2 = Carriers
1/2 = Affected
All = Affected
The table shows the desirable breedings (gray-shaded boxes) which have at least one parent that is Normal by the OptiGen CEA/CH test. All other breedings are at risk of producing pups affected with CEA/CH.

Source:Optigen

Breeder's Note: It is VERY good news knowing that if you breed a normal to a normal none of the puppies will have CEA! and even though Optigen indicates in their table that all the gray areas are "desirable breedings" as a breeder I don't think I would breed an affected knowingly to produce puppies that are carriers of CEA. OFA will clear by parentage for first generation puppies.

Collie Eye Anomaly (CEA) Testing Requirements and Cost

Rev. 15 January 18



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