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Eye Problems in the Collie

 

Frequently Asked Questions

I just learned that Collies tend to have bad eye sight. I've read many books on collies and never came across this type of info...far as I can remember. Is this true? How do you go about checking your collie's sight or should I take her to a vet to have it checked? I mean, is it a problem with cataracts--something I'd notice? Does it occur in older collies? My collie seems to be okay as far as I can tell... Her parents checked out to be over-all very healthy...Grand CHs...not that *that* has anything to do with it. Actually, I have noticed that she has a hard time judging distance, but I think that has to do with her long muzzle and not an actual sight problem.

Darlene

Dear Darlene,

Collies are predisposed to two major types of eye problems. The first is called Collie Eye Anomaly (CEA) and the second is Progressive Retinal Atrophy (PRA). In addition, Collies are over represented among dogs with Nodular Granulomatous Episclerokeratitis (NGE).

Collie Eye Anomaly

Collie Eye Anomaly is an inherited disease characterized by abnormal development of the eye. The condition can be detected by examination of the retina of the eye as early as 5 to 8 weeks of age. Milder cases are characterized by choroidal hypoplasia - lack of development of the choroid which is the vascular layer of the back of the eye, and vascular tortuosity. More severe cases may have patchy areas where the choroid is lacking and bare sclera is visible.

Colobomas are outpouches of the sclera, and this is a more serious manifestation of CEA. The colobomas may be small or large and may affect the optic disc or be adjacent to the optic disc. Dogs with colobomas have a greater risk of development of a retinal detachment or retinal hemorrhage or both which often results in blindness.

Most Collie breeder have pups checked before selling them, by a veterinarian specialized in ophthalmology. The colour dilute (merle) collies may be a challenge in interpretation by the inexperienced examiner. In addition, some affected collies may develop some pigmentation in the retinal pigmented epithelium (RPE) over areas of choroidal hypoplasia making them look better than they really are. Breeders call these dogs "go normals" but genetically they are affected. It is therefore important to check the pups when they are about 6 weeks of age.

Because CEA has involved so much of the breed, eradication has had to be slow in order to keep other desirable qualities. Even among the dogs that examine clear, most are carriers of the gene. The Collie Club of America encourages its members to have all their puppies checked as young as possible by a veterinary ophthalmologist. No dog should be used for breeding until examined and found to be above the examiner's standard. Interestingly, the incidence of Collie Eye Anomaly in Britain is much less than in North America.

Progressive Retinal Atrophy

Progressive Retinal Atrophy is an inherited degeneration of the retina called Rod-Cone Dysplasia type 2. By 6 weeks of age the pup may show signs of nightblindness, with marked visual impairment apparent in the first year. Obvious signs of retinal degeneration is evident on eye examination by 3 to 4 months of age, and an electroretinogram performed as early as 6 weeks of age is diagnostic for the disease.

Nodular Granulomatous Episclerokeratitis

Nodular Granulomatous Episclerokeratitis (sometimes called Nodular Fasciitis, Fibrous Histiocytoma or Collie Granuloma) is thought to be an immune mediated disorder where a cellular proliferation occurs at the corneal scleral junction, and can invade into the cornea causing damage. Interestingly, many collies with "Collie Nose" - depigmented ulcerated lesions at the nose will also have "Collie Granuloma" - NGE. The condition is treated with topical or systemic anti-inflammatories or in severe cases immunosupressives.

Persistent Pupillary Membranes

Persistent Pupillary Membranes (PPM's) are strands of residual iris tissue important in the development of the iris but which fail to go away after birth. Some PPM's are iris to iris and are harmless other than our concerns about the heritability of the problem. Other PPM's may connect iris to cornea causing a corneal opacity, and in some cases the PPM may connect iris to lens resulting in a cataract. In the Basenji and the Chow, dogs with PPM's are not recommended for breeding. At this time, this recommendation is not extended to the Collie, but experience has shown that we should not be complacent about this problem. Certainly a dog with PPM's should not be bred to another dog with PPM's.