What is Collie Eye Anomaly?
Collie Eye Anomaly (CEA), also known as choroidal hypoplasia, is a hereditary congenital ailment. Typically evident from birth in afflicted canines, CEA stems from a genetic mutation. It commonly impacts both eyes, though severity can differ between them.
The condition arises due to flawed development of blood vessels in the choroid, the tissue layer at the back of the eyeball responsible for supplying nutrients to the retina, the light-sensing part of the eye. This aberration leads to impaired retinal function and creates blind spots in the visual field. In severe cases, detachment of the choroidal layer from the retina may culminate in blindness.
Choroidal hypoplasia can suddenly manifest in puppies due to abnormal intrauterine development. Maternal factors such as poor health during pregnancy, exposure to toxins, infections, or inadequate nutrition, can contribute to this occurrence. Regardless of the cause, inadequate development of the choroidal vessel layer results in retinal complications in affected dogs.
Aside from Rough and Smooth Collies, breeds susceptible to this condition include Shetland Sheepdogs (Shelties), Australian Shepherds, and Border Collies. Some breeds less commonly affected by the gene mutation include Lancashire Heelers, Boykin Spaniels, Longhaired Whippets, Hokkaidos, Silken Windhounds, and Nova Scotia Duck Tolling Retrievers. Additionally, mixed breed dogs with Collie-type lineage may also be at risk of carrying the gene.
While Collie Eye Anomaly (CEA) typically doesn’t cause pain, affected dogs may suddenly go blind due to retinal detachment. Although retinal detachment itself isn’t painful, it can lead to bleeding in the back part of the dog’s eye, known as the fundus. The accumulation of blood inside the eye can result in increased intraocular pressure, leading to glaucoma, which can be extremely painful for the dog.
If left untreated, retinal detachment may progress to blindness or necessitate surgery to remove the affected eye (enucleation) if the pain cannot be adequately controlled.
Symptoms
Signs of Collie Eye Anomaly may encompass:
- Microphthalmia: Abnormally small eyeballs compared to the norm.
- Anophthalmia: Eyeballs that appear sunken.
- Cloudy appearance in the eyes.
- Coloboma: A gap or hole in the retina.
- Retinal folds, which develop when the retinal tissue exceeds the eye’s capacity. This issue often resolves by the time the dog reaches 12 weeks of age, underscoring the importance of early evaluation by a veterinary ophthalmologist for an accurate diagnosis.
- Retinal detachment.
Causes
The cause of Collie Eye Anomaly (CEA) stems from a DNA mutation. It is an autosomal recessive condition, which implies that affected puppies inherit a copy of the mutated gene from both parents. Inheritance occurs when a puppy receives one copy of the mutated gene from each parent, leading to the manifestation of symptoms.
Puppies inheriting one normal gene and one mutated gene are carriers of CEA. Although carriers don’t exhibit symptoms, they can still pass on the mutated gene to their offspring if they mate with another carrier later in life.
CEA is typically not progressive, meaning that symptoms present at birth generally do not worsen with age. Some symptoms, such as retinal folds, may even resolve as the puppy matures. However, if an affected dog experiences retinal detachment, it can progress to complete and irreversible blindness.
Diagnosis
Veterinary ophthalmologists can diagnose Collie Eye Anomaly (CEA) as early as six to eight weeks of age in dogs. They typically employ eye drops to dilate the pupil, facilitating a thorough examination using an ophthalmoscope—a specialized tool for observing the back of the eye. This examination aims to detect abnormalities such as retinal folds, underdeveloped choroidal blood vessels (choroidal hypoplasia), and colobomas.
It is recommended that puppies undergo examination by a veterinary ophthalmologist before they reach 12 weeks of age to ascertain a diagnosis. During the examination, the ophthalmologist administers drops to dilate the puppies’ pupils, similar to those used in human eye exams. This dilation enables the veterinarian to inspect the back of the eye for any irregularities concerning the retina, choroidal blood vessels, and optic nerve.
Furthermore, carriers of CEA can be identified through genetic testing, which boasts an accuracy rate of up to 95%. This genetic testing necessitates a blood sample, which can be collected by a veterinarian for analysis.
Owners of at-risk puppies should remain vigilant for signs of impaired vision, which may manifest as behavioral changes such as:
- Clumsiness, such as bumping into furniture or walls.
- Difficulty judging distances while jumping or navigating stairs.
- Trouble locating toys or food/water bowls.
- Anxious behavior in new environments or around unfamiliar individuals or animals.
- Reluctance or refusal to venture outdoors.
- Alterations or decreases in typical play behaviors.
Physical indicators may include cloudiness in the eyes, smaller eyeballs (microphthalmia), or a visibly sunken appearance (anophthalmia) in the puppy’s eyes.
Treatment
Treatment options for Collie Eye Anomaly (CEA) are limited:
- There is currently no cure for Collie eye anomaly.
- However, if a puppy with CEA still retains some vision, veterinarians can employ treatments to potentially preserve vision in the long term, should complications arise.
- It’s important to note that the disease itself cannot be reversed.
- Depending on the severity of symptoms, prescription eye medications may offer some relief, particularly if glaucoma develops. Pet owners should consult with a veterinary ophthalmologist to assess the suitability of such medications for their dog.
- Generally, the overall quality of life for dogs with CEA isn’t significantly affected, as vision issues typically arise shortly after birth.
- CEA is not inherently painful and doesn’t cause discomfort unless complications like retinal detachment, bleeding into the eye, or increased intraocular pressure leading to glaucoma occur.
- Laser surgery can be beneficial in repairing partial retinal detachment resulting from colobomas in some cases.
- Cryosurgery presents another option for repairing partial retinal detachments, aiming to prevent complete detachment by freezing tissue cells to create scar tissue, which aids in reattaching loose portions of the retina to the eye’s back, thereby preserving vision.
Living and Management
The management and recovery of Collie Eye Anomaly (CEA) typically involve implementing lifestyle adjustments for affected dogs, encompassing both indoor and outdoor routines. Here are some suggestions to ensure your dog’s safety and well-being:
- Maintain consistent furniture arrangements throughout the house.
- Use dog gates strategically to prevent accidental falls, particularly on staircases.
- Install fencing around pool decks to mitigate the risk of accidental drowning.
- Keep their food, water, and bedding in fixed locations to reduce anxiety related to spatial orientation.
- Consider using Halo devices to safeguard dogs from bumping into sharp objects or corners at eye level.