CEA is a disorder of the deep
structures of the eye that affects collie breeds around the world. The
four main changes are:
inadequate development of the choroid, a thin layer of blood vessels
that delivers oxygen and nutrients to the retina (called hypoplasia of
the choroid or chorioretinal dysplasia);
coloboma - a cleft or defect of the optic disc or adjacent areas;
staphyloma - an area of thinning in the sclera which is adjacent to the
choroid; and
retinal detachment with or without haemorrhage - a complication
associated with the other defects.
In its mildest form, there are minor changes in the choroid which will
have little effect on sight. About 25 per cent of dogs with CEA have
colobomas/staphylomas as well as choroidal hypoplasia. Retinal
detachments occur in approximately seven per cent of dogs with CEA.
Total retinal detachment will cause blindness.
How is collie eye anomaly inherited? Inheritance is autosomal recessive with variable expression
and pleomorphism (meaning that there is a wide range in clinical
expression of the defect).
What breeds are affected by collie eye anomaly? The disorder occurs commonly in collie breeds, including the border
collie, rough collie, smooth collie, and Shetland sheepdog. The
best way to avoid this problem is to purchase a pup from parents that
have been registered with the Canine Eye Registration Foundation
(CERF), and have
never produced affected pups.
A similar condition has been seen, although very rarely, in the borzoi,
Australian shepherd, beagle, dachsund, German shepherd, and miniature
and toy poodle.
For many breeds and many disorders, the studies to determine the mode
of inheritance or the frequency in the breed have not been carried out,
or are inconclusive. We have listed breeds for which there is a
consensus
among those investigating in this field and among veterinary
practitioners,
that the condition is significant in this breed.
What does collie eye anomaly mean to your dog & you?
Many dogs will have apparently normal vision unless retinal detachment
with or without haemorrhage occurs, causing blindness in the affected
eye. Retinal detachments are often one-sided and generally occur before
2 years of age.
How is collie eye anomaly diagnosed?
Your veterinarian will be able to see the abnormalities in the back of
the eye with an ophthalmoscope.
FOR THE VETERINARIAN: choroidal hypoplasia - appears as an area lateral (temporal) to
the optic disc with reduction or absence of pigment so that the
underlying choroidal vasculature is seen; the choroidal vessels may be
reduced in number and of abnormal shape; may see underlying white
sclera. Once the retina changes
to its adult colour (about 3 months of ages), the normal pigment in the
retina may mask the changes in the choroid (so-called "go normal") coloboma - appears as an excavation of the optic disc surface
and sometimes adjacent ocular fundus
retinal complications - detachment with or without haemorrhage
How is collie eye anomaly treated?
There is no treatment.
Breeding advice
Minor lesions may not be detectable by ophthalmoscope after 3 months of
age, so collies intended for breeding programmes should be examined
early at 5-6 weeks of age. Even dogs with minor lesions (mild choroidal
hypoplasia) should not be bred because their offspring may be affected
with more serious forms of the disorder.
Because of the potential for serious eye disease with this trait,
neither affected dogs, their parents, or their offspring should be used
for breeding. Siblings of affected dogs should not be used either,
unless eye exams before 3 months of age demonstrate that they are
unaffected.
FOR MORE
INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
Where to find more information?
Gelatt, K.N. 1991. Veterinary Ophthalmology. p. 473-477. Lea and
Febiger.
The above information is simply informational. It's intent is
not to replace the advice of a veterinarian nor to assist you in making
a diagnosis of your pet. Please consult with your own veterinarian for
confirmation of any diagnosis. Your pets life may depend on it.
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