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Friday, June 20, 2014

CEA - Collie Eye Anomaly




What is CEA?  CEA stands for Collie Eye Anomaly, a disease that is commonly seen in collies.  However, collies are not the only breed to suffer from this disease.  CEA is actually a group of eye conditions, ranging from mild to severe.  Fortunately, it is easily detected with an eye examination by a Canine Ophthalmologist.  The test should be done by the breeder, when the puppies are 5 - 6 weeks old.  Reputable, ethical breeders will have their puppies tested before they are sold to new families.  The good news is that most CEA does not impair the dog’s vision, so owners will rarely see any discernable difference between collies with CEA and those who are normal eyed.

 
The Collie Club of America's Code of Ethics requires that all dogs that are sold or placed, be in good condition, free of communicable diseases with their health guaranteed for a reasonable length of time.  This should include a written health record, inoculation schedule and the results of the eye exam.  If a breeder refuses to provide you with the puppy's health record or results of the eye exam, then you may want to find another breeder.

 
When tested for CEA the puppies will be given either a "normal" or "affected" rating.  If affected, the type of abnormality will be noted.

 Normal: This is what collie breeders hope to produce, a “normal-eyed” collie puppy with no CEA.  A "Normal" eye rating is the best rating.  There are also "Go Normals", which are so mildly affected at a young age, that later, the pale areas caused by choroidal hypoplasia disappear, leading to what is termed a "Go Normal."  These “go normal” puppies are still affected with CEA, and can pass CEA onto their future offspring.  The only way to be certain a collie is not a carrier of CEA is through genetic testing.  Also, dog's coat color can make it difficult to get 100% accurate results, as the pigment in a Blue Merle's eyes can be diluted along with his coat color.

 Choroidal Hypoplasia, Chorioretinal Change: These refer to abnormalities in the coloring or pigmentation of the choroid or central layer of the eye's lining. This is the most common abnormality found in Collie eyes.  It is the least harmful and least severe form of CEA.  Most dogs with this eye grade, function normally with no ill-effects or vision impairment.  These puppies are carriers of CEA.

 Staphyloma, Coloboma, Ectasia: While not completely synonymous, these terms all refer to a cupping or bulging in the eyeball usually in the area of the optic disc.  They can appear to be “pits” or “holes” in the layers of the eye tissue.

 Vascular Disease, Tortuous Blood Vessels: Defects in the vessels of the eye which are responsible for its blood supply or "nourishment." These may be malformed, undersized, or even lacking.

 Retinal Detachment: Loosening or separation of the inmost, or retina, layer from the wall of the eye. This may involve a tiny area or the entire retina. It can be either one or both eyes. The complete detachment of the retina results in blindness in that eye.

 
CEA is a recessive trait, and even dogs that are "normal" on ophthalmoscopic examination can still be carriers of CEA, and about 90% of the collie breed are carriers.  A dog with one mutant copy of the CEA and one normal copy of CEA is called heterozygous, or a CEA carrier. A dog with two copies of the normal CEA gene is homozygous, or genetically free of CEA.  Only dogs that are normal or who have choroidal hypoplasia should be used for breeding.  Dogs with colobomas, staphylomas, ectasia or detachments should not be bred, as they will pass these more severe issues along to their offspring. 

 
PRA, Progressive Retinal Atrophy, is another eye condition.  It is unrelated to CEA, and it is a degenerative disease that can result in blindness.  Most dogs with PRA will be blind by the time they are a year old.  You can learn more about PRA, by visiting this site:

2 comments:

  1. Bowsers, that is a lot of fancy words. Glad I have normal eyes.

    Sherman

    ReplyDelete