Collie Eye Anomaly
Collie eye anomaly (CEA), or collie eye defect, is an inherited chromosomal condition that affects the development of the eyes in certain dog breeds. The disorder occurs worldwide and is diagnosed in various types of collies, Australian shepherds, Shetland sheepdogs, Lancashire heelers and others. The symptoms of CEA may vary from virtually none at all to total blindness.
CEA is caused by a genetic anomaly in the 37th canince chromosome. It is considered an autosomal recessive trait, meaning that both parents must possess the mutated gen to pass it on to the offspring.
Some dogs who carry the affected gene show no symptoms at all at first, but may start showing symptoms as the eye develops. A thinning choroid (the group of blood vessels that supply the retina) is the telltale sign of CEA. Other possible symptoms include varying stages of blindenss, corneal mineralization, retinal detachment, enophthalmis (sunken eyeballs) and microphthalmia (abnormally small eyeballs). Coloboma (hole in the tissue) of the retina, iris, optic disc, lens, or orther parts of the eye is also possible.
A thorough eye examination is the frist step in diagnosing collie eye anomaly. Funduscopy, which examines the retina or bakc portion of the eyeball's interior using an ophthalmoscope, is also used. Other possible causes of eye issues or blindess like disease, infection or injury must be ruled out. Since 2005, a test has existed that can screen for the presence of the CEA gene. In addition to helping diagnose the condition, this test is useful when determining is a dog is safe for breeding. Genetic testing and eye examinations are recommended for potentially affected breeds as early as five to eight weeks of age.
There is no specific treatment for collie eye anomaly, but steps can be taken to minimize the condition's effects on a dog. Laser surgery, retinal reattachent and other steps may be able to resolve certain symptoms in the eye. Otherwise, treatment is supportive in nature.
The only way to entirely prevent collie eye anomaly is to avoid breeding two affected dogs. This can be difficult because of CEA's wisespread presence. In addition; some breeder breed mildly affected dogs in hopes of producing only mildly affected offspring. However, breeding two mildly affected dogs does not necessarily mean the offspring will only have a minor form of the condition, it is entirely possible for the offspring to have sever CEA even if both parents have the mildform. Genetic testing to determine whether or not dogs posses the CEA gene is highly recommended before mating breeds that are likely to have the mutation.