Border Collie CEA (Collie Eye Anomaly) — A Complete Guide from Screening Timelines to Genetic Management

Eye HealthBreed HealthMeongsiljang Veterinary Advisory Board

We’ve put together a comprehensive guide covering the definition of CEA, a common hereditary eye condition in Border Collies, as well as screening timelines, the differences between fundus and genetic testing, and important considerations for breeding.

Understanding Border Collie CEA at a Glance

A young Border Collie waiting for its checkup

Collie Eye Anomaly (CEA) is a congenital, hereditary eye condition in Border Collies that occurs when ocular tissues develop abnormally during fetal development. Although it affects both eyes, the severity often differs between them. The most critical factor is the timing of screening. An ophthalmic fundus examination by a veterinary ophthalmologist is recommended at around 6 to 8 weeks of age. If follow-up exams are delayed until between 6 months and 1 year of age, minor lesions or retinal folds may no longer be visible due to a phenomenon known as "going normal." Therefore, the initial examination performed at a young age is crucial. Since CEA is commonly reported in herding breeds such as Border Collies, Collies, and Shetland Sheepdogs, it is essential to have this condition checked during your puppy’s first veterinary visit after acquisition.

Why Does It Occur Frequently in Border Collies?

Collie Eye Anomaly (CEA) is a hereditary eye condition caused by inheriting the causative gene from parents. A gene deletion of approximately 7.8 kb has been reported to be inherited alongside CEA across various breeds, and the disease can manifest in some puppies when both parents are carriers. According to veterinary ophthalmology textbooks and related research, CEA is particularly prevalent in herding breeds such as Border Collies, Rough Collies, Shetland Sheepdogs, and Australian Shepherds, and selective breeding is known to influence the prevalence of this condition. The severity of the disease varies widely, ranging from mild choroidal hypoplasia to blindness caused by retinal detachment.

Signs Owners Can Notice

CEA can affect both eyes, but the severity often differs between them. Since the condition isn't always obvious, many dogs show no clear symptoms. However, if you notice any of the following signs, a veterinary ophthalmology consultation is necessary: - Bumping into walls or furniture: Collisions in familiar areas due to narrowed vision - Difficulty adapting to darkness: Getting lost or hesitating during evening walks - Signs of bleeding in the eye: A red appearance caused by hyphema (anterior chamber hemorrhage) accompanying retinal detachment - Behavior suggesting sudden blindness: Inability to locate the direction of your voice While mild cases may allow for normal vision throughout life, larger colobomas can lead to vision loss due to retinal detachment.

The Golden Time for Screening Is 6–8 Weeks of Age

CEA fundus examinations are most recommended at around 6 to 8 weeks of age. As time passes, some mild lesions or retinal folds may no longer be visible on follow-up exams between 6 months and 1 year of age. Due to this "Go Normal" phenomenon, puppies with CEA may actually be classified as normal. Therefore, the initial exam results from early in life are crucial. If diagnosis through fundus examination alone is difficult, a separate genetic test should be performed to more accurately determine carrier status. If you are considering acquiring a puppy, be sure to request the health screening results for both parent dogs from the breeder.

How Is It Tested?

There are two ways to diagnose CEA. The first is a dilated fundus examination, in which a veterinary ophthalmologist dilates the pupil with mydriatic drops and directly visualizes the posterior pole of the retina using an ophthalmoscope or slit lamp. The second is a genetic test that checks for mutations in the NHEJ1 gene using a cheek swab or blood sample. The fundus examination reveals the phenotype (whether actual lesions are present), while the genetic test determines the genotype (carrier status). Combining both tests provides the most accurate assessment of your pet’s condition.

Fundus Examination vs. Genetic Testing

Item	Dilated fundus exam	Genetic test (NHEJ1)
What it checks	Presence of actual retinal lesions	Genotype (normal/carrier/affected)
Recommended timing	6–8 weeks of age	Possible at any age
Test method	Fundus observation after pupil dilation	Buccal swab or blood draw
Advantages	Directly confirms lesion severity	Not affected by 'Go Normal'
Limitations	Mild lesions may appear to disappear after 6 months to 1 year of age	Cannot determine lesion severity
For breeding decisions	Supplementary data	Essential data

Doing both tests together is the most accurate.

How to Interpret Screening Results

Fundus lesions are classified by stage. The most common is choroidal hypoplasia (CH), a thinning of the blood vessel layer behind the retina, which often has little impact on vision. As the condition progresses, it can lead to coloboma, a depression around the optic disc, retinal vascular abnormalities, and even retinal detachment. Genetic test results fall into three categories: clear, carrier, and affected. Even in affected dogs, lesions may be mild, so a comprehensive assessment combining genetic and fundus examination results is essential.

A Border Collie undergoing a fundus examination with a slit lamp

Be Sure to Verify Before Breeding or Rehoming

CEA is a genetic disorder, so it’s essential to verify the screening results of both parent dogs before breeding. Mating two carriers can result in 25% of their puppies being affected. If you’re considering getting a Border Collie, ask for an ophthalmic examination certificate from the American College of Veterinary Ophthalmologists (ACVO) or an equivalent accredited institution in Korea, along with the NHEJ1 gene test results. It’s wise to carefully reconsider any breeder who cannot provide both documents.

Lifelong Management Points After Screening

CEA is a congenital condition rather than a progressive disease, so once diagnosed, new lesions will not develop. However, dogs with large colobomas are at risk of retinal detachment during growth, making annual fundus examinations essential. In daily life, minimize strong impacts such as high jumps and rough play, and seek immediate veterinary ophthalmic care if you notice sudden vision changes, unequal pupil sizes, or conjunctival redness. Since Border Collies are highly active, it is also advisable to include regular hip and elbow screenings alongside eye check-ups.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

How much does the checkup cost?

At ophthalmology specialty hospitals, fundus examinations are typically performed as an add-on to the basic consultation fee. Genetic testing incurs a separate kit fee, and results are usually available within 2 to 4 weeks. Exact costs vary by hospital and testing facility, so please confirm in advance.

My dog is already an adult. Should I still get him tested now?

In adult dogs, the "Go Normal" phenotype limits the diagnostic value of fundus examinations alone, so we recommend prioritizing NHEJ1 genetic testing. This test is especially important if you're planning to breed or if the puppy's parental information is uncertain.

Can a dog with CEA still live a normal daily life?

Yes, it's possible. If your pet only has choroidal hypoplasia (CH), the most common form, their vision is usually nearly normal. However, if coloboma or retinal detachment is present, vision loss or even blindness can occur, so regular monitoring is essential.

Can it be confused with other eye diseases?

Yes, the symptoms can look similar to those of progressive retinal atrophy (PRA), glaucoma, and cataracts. However, since CEA is congenital and PRA progresses gradually, an ophthalmologist can differentiate between them through a fundus examination.

Is there a way for pet owners to check this at home in advance?

You can observe whether your dog avoids obstacles in a dark room, if their left and right visual field responses are symmetrical, and whether their pupils are equal in size. However, since a definitive diagnosis of CEA is difficult without a fundoscopic examination, it is essential to have your dog evaluated at a veterinary clinic.

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References

[1] Esson DW, Calvarese S. Clinical Atlas of Canine and Feline Ophthalmic Disease, 2nd Edition, Chapter 134 Collie Eye Anomaly. John Wiley & Sons, 2022

[2] Lowe JK, Kukekova AV, Kirkness EF, et al. Linkage mapping of the primary disease locus for collie eye anomaly. Genomics. 2003;82(1):86–95

[3] Parker HG, Kukekova AV, Akey DT, et al. Breed relationships facilitate fine-mapping studies: a 7.8-kb deletion cosegregates with Collie eye anomaly. Genome Research, 2007

[4] Munyard KA, Sherry CR, Sherry L. A retrospective evaluation of congenital ocular defects in Australian Shepherd dogs in Australia. Vet Ophthalmol. 2007;10(1):19–22