Collie Eye Anomaly
What is it?
- Collie eye anomaly is a inherited congenital eye disease found in Collies, Shetland Sheep dogs and Border Collies along with Australian Shepherds.
- Non progressive
- Condition is bilateral (in both eyes) but often one eye is more severe than the other.
- Caused by improper development of the eye, more specifically the choroid, which is a collection of blood vessels within a layer of tissue that is located right behind the retina.
- There is no treatment for CEA
In the United States:
- up to 97% of Rough Collies are affected but only 2-4% have vision impairment or blindness.
In the United Kingdom:
- Shetland Sheepdog is the breed with the highest incidence of CEA and Rough Collies are much lower than the united states.
Problems with CEA
- This is the thinning of the vascular tissue in the back of the eye which doesn't significantly impure vision in the dog.
Some dogs will also have optic nerve coloboma.
- This is where the nerve tissue doesn't fully develop around the area of the eye where the optic nerve enters.
- This can cause the dog to have a hole in their eye, small holes can cause no vision impairment but large hole can lead to complete blindness.
- This can also cause retinal detachment in severe cases.
Diagnosis and Testing
- Puppies usually appear normal because few have actual vision impairment.
- Veterinarians or DNA tests are the only way to diagnosis.
- Puppies need to routinely be check, especially between 6-8 weeks of age because this is when it will be easiest to find and has the least chance of miss diagnosis.
- Pigmentation (pale spot) will appear lateral to the optic disk due to the underdevelopment of the choroid in the eye.
- DNA testing is available to see if your dog is affected, is a carrier of CEA or is clear of the mutation.
- Companies use a panel of 6 DNA markers called a haplotype to test for the DNA mutation.
- Testing is available for Rough and Smooth Collies, Australian Shepherds, Border Collies, Lancashire Heelers and Shetland Sheepdogs
Not sex linked
Caused by mutation on the canine chromosome 37
- Affected dogs: have 2 copies of the mutant gene and is homozygous for CEA. Will pass the CEA mutated gene to offspring.
- Carrier dogs: have 1 normal gene and 1 mutated gene. Can pass defective gene to offspring (50% chance).
- Clear dog: negative for mutated CEA gene and can't pass mutation on to offspring.
- 50% clear of the CEA mutation
- 50% carriers of the CEA mutation
If you breed two heterozygous dominant collies:
- 25% clear of the CEA mutation
- 50% carriers of the CEA mutation
- 25% affected with CEA
The only way to eradicate or lower CEA is to stop breeding Collies with the mutation or ones that are even carriers to the mutation.
- The chart below shows the percentages when breeding dogs with or without the CEA mutation.
This is hard to do because some dogs are misdiagnosed by veternarians so breeders don't believe they can pass it on when they can.
"Collie Eye Anomaly." Australian Shepherd Health Genetics Institute. Australian Shepherd Health Genetics Institute, 1 Mar. 2013. Web. 27 Apr. 2015. <http://www.ashgi.org/home-page/genetics-info/eyes/collie-eye-anomaly#>.
Barnett, K. "Collie Eye Anomaly (CEA)." Journal of Small Animal Practice 20.9 (2008): 537-42. Print.
Oliver, James, and Dennis Brooks. "Collie Eye Anomaly." Vetstream. Web. 27 Apr. 2015. <https://www.vetstream.com/canis/Content/Disease/dis00527.asp>.
"Collie Eye Anomaly (CEA)." Collie Eye Anomaly (CEA). Animal Genetics Inc. Web. 27 Apr. 2015. <http://www.animalgenetics.us/Canine/Genetic_Disease/CEA.asp>.
"Collie Eye Anomaly (CEA)." Pet Health Network. 29 Aug. 2012. Web. 27 Apr. 2015. <http://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/collie-eye-anomaly-cea>.
Collie Eye Anomaly. Digital image. Dogtime. Web.
Collie Eye Anomaly (CEA). Digital image. Pet Health Network. 29 Aug. 2012. Web.
Collie Eye Anomaly. Digital image. Australian Shepherd Heath and Genetic Institute. 1 Mar. 2013. Web.