Collie Eye Anomaly (CEA), also known as Collie Eye Defect, is a hereditary condition that affects the development of the eye in certain dog breeds, most commonly Collies. This genetic disorder impacts the retina, choroid, and sclera, leading to vision impairment and, in severe cases, blindness. Understanding the condition is essential for dog owners, breeders, and veterinarians to manage and prevent complications effectively.

In this article, we will explore the key aspects of Collie Eye Anomaly, including its causes, symptoms, diagnosis, and management strategies.

Collie Eye Anomaly is a congenital disorder that causes underdevelopment in parts of the eye responsible for vision. The condition primarily affects the choroid, the layer of blood vessels between the retina and the sclera (the white part of the eye). CEA is considered a complex genetic disorder because it presents in various degrees of severity, ranging from mild to severe ocular issues.

The anomaly is seen predominantly in Collies but can also affect other herding breeds such as Shetland Sheepdogs, Border Collies, and Australian Shepherds. Because it is a recessive genetic disorder, both parents must carry the gene for the disease to be passed on to their offspring.

CEA is caused by a mutation in a gene located on chromosome 37. This mutation disrupts the normal development of the eye, particularly during the embryonic stage, leading to structural defects in the choroid and retina. The defective gene is autosomal recessive, meaning a dog must inherit two copies of the mutated gene (one from each parent) to exhibit symptoms of the condition. Dogs that inherit only one copy of the gene become carriers, but they do not display symptoms.

Due to the hereditary nature of CEA, selective breeding is the most effective way to prevent the spread of the condition. Responsible breeders screen for the gene before mating to minimize the risk of producing puppies with the disorder.

The symptoms of CEA can vary depending on the severity of the defect. In mild cases, dogs may show no obvious signs of vision impairment, while more severe cases can result in significant vision loss or even total blindness. Here are the most common symptoms:

• Choroidal Hypoplasia: This is the hallmark of CEA and refers to the underdevelopment of the choroid. It leads to a thinner, less functional blood supply to the retina, resulting in vision issues.
• Coloboma: This is a defect in the optic disc or retina that can cause gaps or holes in the eye structure, leading to vision impairment.
• Retinal Detachment: In severe cases, the retina may become detached from the underlying tissue, which can result in complete blindness.
• Vision Loss: Depending on the severity, dogs may experience partial or total blindness, particularly in both eyes.
• Abnormal Eye Movements: Dogs with CEA may exhibit abnormal or uncontrolled movements of the eyes due to neurological involvement in some cases.

CEA is typically diagnosed through a detailed eye examination by a veterinary ophthalmologist. Because the condition is present at birth, puppies can be screened as early as six to eight weeks old. During the exam, the veterinarian will use specialized instruments to examine the internal structures of the eye, including the retina and choroid.

Diagnostic tools used to confirm CEA include:

• Ophthalmoscopy: A thorough examination of the retina using an ophthalmoscope helps detect abnormalities like choroidal hypoplasia or coloboma.
• Ultrasound: If retinal detachment is suspected, an ocular ultrasound can help visualize the extent of the damage.
• Genetic Testing: DNA testing is a valuable tool in detecting whether a dog is a carrier, affected by, or clear of the CEA gene mutation. This can help breeders make informed decisions about their breeding practices.

There is no cure for Collie Eye Anomaly, but treatment options depend on the severity of the condition and the symptoms exhibited by the dog. In mild cases, where the dog’s vision is not significantly impacted, no treatment may be necessary. However, in more severe cases, intervention may be required to preserve the dog’s quality of life.

• Surgical Intervention: In the case of retinal detachment, surgery may be required to reattach the retina and prevent further vision loss. This procedure is complex and not always successful, depending on the extent of the detachment.
• Medications: Anti-inflammatory medications or corticosteroids may be prescribed to reduce swelling and manage secondary complications like glaucoma.
• Supportive Care: For dogs with vision impairment or blindness, owners can implement certain lifestyle adjustments, such as keeping the home environment predictable and avoiding obstacles to help the dog navigate safely.

Preventing CEA relies heavily on responsible breeding practices. As CEA is an inherited condition, genetic testing of breeding pairs is crucial to reducing the incidence of the disorder in future generations. Breeders should avoid mating two dogs that are carriers of the CEA gene to prevent the risk of producing affected puppies.

Here are some steps to prevent CEA through breeding practices:

• Genetic Screening: Testing breeding dogs for the CEA gene helps identify carriers and ensure that only dogs without the gene or with only one copy are bred.
• Breeding with Clear Dogs: When breeding, choosing dogs that are clear of the CEA gene ensures that puppies will not inherit the disorder.
• Early Puppy Screening: Conducting eye exams on puppies at an early age helps breeders identify whether they are affected by CEA, allowing for proper care or selective breeding.

Collie Eye Anomaly is a genetic disorder that can cause varying degrees of vision impairment in affected dogs. While there is no cure, early diagnosis and responsible breeding practices can help reduce the spread of the condition and manage its impact on affected dogs. By understanding the causes, symptoms, and treatment options, dog owners and breeders can take proactive steps to care for dogs with CEA and improve their quality of life.

World Eye Care Foundation’s eyecare.live brings you the latest information from various industry sources and experts in eye health and vision care. Please consult with your eye care provider for more general information and specific eye conditions. We do not provide any medical advice, suggestions or recommendations in any health conditions.