Collie eye anomaly: diagnosis and age at screening

Question

Eye screening of a litter of 7-week-old Border Collies. One puppy has, in both eyes, a pale area lateral to the optic disc in which choroidal vessels are seen against a white scleral background. The optic discs are normal and there is no detachment.

Which statement is correct?

chevron_right Show answer and explanation

A. It is a progressive degeneration and the puppy will go blind as in progressive retinal atrophy

Collie eye anomaly is congenital and non-progressive. Isolated choroidal hypoplasia does not affect vision; only cases with large colobomas, detachment or haemorrhage compromise it.

B. It is inherited dominantly, so it is enough not to breed from the affected parent

It is autosomal recessive (deletion in NHEJ1): the parents of an affected puppy are at least carriers even if their eyes are normal.

C. If the fundus is normal at 12 months, the dog is free of the disease

As the fundus pigments at about 3 months, mild hypoplasia may become masked ('go normal'). A normal adult fundus does not exclude affected status; the DNA test settles it.

D. It is choroidal hypoplasia from Collie eye anomaly; it is best detected at 6–7 weeks and there is a DNA test for breeding

Correct. Choroidal hypoplasia lateral to the disc is the typical lesion. Examining before the fundus pigments and using the NHEJ1 test in breeding dogs helps control the disease in Collies, Shetland Sheepdogs, Border Collies and Australian Shepherds, among others.

lightbulb Key takeaway

Collie eye anomaly ranges from inconsequential choroidal hypoplasia to optic disc colobomas, retinal detachment and intraocular haemorrhage. Severity cannot be predicted from genotype, so each puppy should be examined as well as tested.

Which statement is correct?

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