While the eye disease may be named for the collie breed, collie eye anomaly (CEA) can actually affect several different dog breeds by being passed down genetically from a litter's parents. Affecting the retina in the dog's eyes, CEA often leads to blindness. This disease is not considered to be treatable, though in some cases, surgery may prevent retinal detachment that causes blindness. Breeds like collies, Shetland sheepdogs, Australian shepherds, border collies, and Nova Scotia Duck Tolling Retrievers are at higher risk of inheriting CEA from their parents. Because it can have serious effects on a dog's vision, it's important for owners of at-risk breeds to understand this condition and know the symptoms associated with it.
What Is Collie Eye Anomaly?
Collie eye anomaly (CEA), also known as collie eye defect, is an eye disease that affects the development of a dog's eye and impairs its vision. It is a genetic disease that some dogs are born with. CEA usually causes the blood vessels inside the eye, which provide blood flow to the retina, to be underdeveloped. This disease can lead to blindness in severe cases when the retina does not receive proper blood flow or becomes detached.
Types of Collie Eye Anomaly in Dogs
Collie eye anomaly is often described as a syndrome because several different eye abnormalities can be classified as a part of this condition:
- Choroidal hypoplasia or chorioretinal changes: These are the most commonly seen abnormalities in CEA, affecting the blood flow to a vascular layer underneath the retina called the choroid. These choroidal issues are considered to be the least dangerous of CEA abnormalities, so dogs do not usually lose their vision.
- Retinal folds: This abnormality occurs when the retina folds in on itself. This condition usually improves with age, so dogs do not usually lose their sight.
- Staphyloma, coloboma, or ectasia: These issues all involve a bulging inside the eye, usually around the optic disc. They can lead to retinal detachment and blindness depending on their severity.
- Vascular disease or tortuous blood vessels: These conditions cause problems with the blood supply in the eye, making the vessels small, underdeveloped, or even nonexistent.
Symptoms of Collie Eye Anomaly in Dogs
Collie eye anomaly is not usually a disease that is obviously seen by pet owners, but occasionally, more obvious eye abnormalities can be seen alongside CEA. Owners may notice issues with the actual appearance of their dog's eyes or observe unusual behavior indicating that the dog's vision is impaired. The following symptoms may be present:
Abnormally Small Eyeballs
Also known as microphthalmia, dogs with collie eye anomaly may have abnormally small eyeballs that is noticeably visible to owners. In these cases, the eyes are underdeveloped, and dogs with this symptom should see a veterinarian to perform further diagnosis.
Sunken In Eyeballs
Enophthalmia causes a dog's eyes to look sunken in, even deep inside the eye sockets. This symptom can be alarming to owners and should always warrant a veterinary exam when observed. Both enophthalmia and microphthalmia can occur in dogs with collie eye anomaly, and these symptoms are the only real visible changes to the eyes that can be seen without special equipment.
Signs of Blindness
Because it causes impaired vision, dogs with collie eye anomaly often exhibit signs of blindness. Blindness is the most common symptom associated with CEA. Your dog may appear stressed or anxious in new places as it can't comfortably navigate the area, or more severely, begin bumping into objects and people around the home.
Causes of Collie Eye Anomaly
Unlike some other diseases of the eye that can be caused by outside factors, collie eye anomaly is always inherited. This is due to a recessive gene that is passed from parent dogs to their offspring, and it is not contagious to other dogs. Puppies that inherit this gene from one parent can be carriers that pass it to another generation when bred, although not all dogs with the gene will display immediate symptoms.
Some dog breeds are more commonly affected than others. If your dog is considered at-risk, it's best to ask your veterinarian about testing to determine whether this disease may begin to present. Owners of dogs that carry this gene should always avoid breeding to prevent the condition from being passed on to the litter.
Breeds that are at higher risk for developing collie eye anomaly include:
Diagnosing Collie Eye Anomaly in Dogs
If your dog is displaying symptoms of collie eye anomaly like enophthalmia, microphthalmia, or signs of blindness, it's important to visit your veterinarian as soon as possible to begin diagnosis. Owners of at-risk dogs should consult their dog's medical provider early in the dog's life to begin screening for this disorder. Dogs can often be diagnosed during a puppy's development between six and eight weeks of age, but a diagnosis might not be possible without genetic testing until signs of impaired vision begin to present.
During the examination, a veterinary ophthalmologist will dilate your dog's eyes. Using an ophthalmoscope, they'll observe the retina to look for changes in the eyes that indicate a case of collie eye anomaly. These changes may include thinning of the tissues around the retina or a coloboma. A coloboma can cause retinal detachment, leading to blindness. Because this condition is inherited, a genetic test must be performed in order to definitively diagnose a dog with collie eye anomaly.
In some instances, surgery is available to prevent retinal detachment if that is a concern for your dog's specific symptoms of CEA. Your veterinarian can determine the specific cause behind your dog's case to provide insight on any available treatment options. Surgery can be effective for dogs with early cases of a coloboma (although this condition does not always cause retinal detachment). However, collie eye anomaly is not generally considered to be treatable, and vision impairment or blindness is common.
Prognosis for Dogs With Collie Eye Anomaly
Collie eye anomaly is not a life-threatening condition, but it can greatly change your dog's lifestyle if blindness occurs. Some dogs may fully lose their vision while others do not, but owners should prepare to help dogs adjust to vision loss in order to lead happy lives even without sight. Thankfully, many dogs are perfectly comfortable after becoming blind once they've developed a new routine at home under their owner's supervision and care.
How to Prevent Collie Eye Anomaly
Selective breeding with the use of genetic testing is currently the only way to decrease the instances of collie eye anomaly being passed to new canine generations. Tests are available to screen dogs before they are bred, which can tell responsible breeders if a dog is simply a carrier or has a form of collie eye anomaly. This test uses a cheek swab or blood sample to look for genetic markers. An eye examination should also be performed by a veterinary ophthalmologist to look for any abnormalities inside the dog's eye.