Collie Eye Anomaly [Choroidal Hypoplasia]
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Breeding advice appliesUse the condition’s screening guidance and veterinary or genetics advice before breeding an affected or at-risk animal.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Collie eye anomaly is an inherited developmental disorder in which structures at the back of the eye do not form normally. It is most strongly associated with Collies and related herding breeds. The defining change is choroidal hypoplasia, meaning that the vascular layer beneath the retina is underdeveloped. The condition is usually inherited as an autosomal recessive trait, although the severity of eye changes is influenced by additional genetic factors.
Affected puppies can show a wide range of severity. Mild dogs may have choroidal hypoplasia with little or no obvious effect on sight. More severely affected eyes can develop an optic nerve coloboma, which is a developmental defect near the point where the optic nerve enters the eye. Retinal bleeding or retinal detachment may also occur. A localised detachment can create a blind area, while complete retinal detachment can cause total blindness in that eye.
One important feature is the “go normal” phenomenon. Choroidal hypoplasia is most visually distinct before the reflective tapetum has fully matured. As pigmentation develops, the abnormal region can become less obvious even though the underlying choroid has not corrected and the dog remains genetically affected. This changing visibility does not alter the inherited defect or eliminate the possibility of coloboma, haemorrhage or retinal detachment in a more severely affected eye.
The condition itself does not usually cause pain, but severe structural complications can permanently affect vision. Its autosomal recessive inheritance allows healthy carriers to pass the altered variant, while dogs with the same genetic status can show different anatomical severity. A mild adult appearance therefore does not mean the developmental defect disappeared. Visual outcome is determined mainly by retinal attachment, bleeding and optic-nerve involvement rather than the superficial visibility of choroidal colour change.
Because the abnormalities develop before birth, the condition does not arise from diet, injury or routine eye disease later in life.
Screening & Early Detection
The most informative clinical screening is an eye examination by a veterinary ophthalmologist while puppies are still young, commonly around six to eight weeks of age. At this stage the choroid can be assessed before full development of the tapetum masks subtle hypoplasia. Waiting until adulthood may miss mild disease because of the go-normal phenomenon.
DNA testing is also available for the recognised Collie eye anomaly mutation in relevant breeds. Genetic testing can identify clear, carrier and genetically affected dogs regardless of whether eye changes are visible on the day of examination. It is particularly useful for breeding decisions because healthy-looking carriers can pass the mutation to offspring. DNA testing and eye examination answer slightly different questions and are most powerful when used together.
Puppies with coloboma, haemorrhage or retinal detachment may need more frequent ophthalmic follow-up because those changes carry greater risk to vision. Also seek prompt assessment if an affected dog suddenly appears visually impaired, develops a change in pupil appearance or begins bumping into objects.
A normal adult eye examination alone should not be used to declare a dog genetically clear if it was never examined as a young puppy. Screening records should therefore include the age at examination and, where available, the dog’s DNA result.
Treatment & Management
An underdeveloped choroid or optic nerve cannot be made to develop normally after birth, so treatment is reserved for complications rather than the congenital defect itself. Dogs with mild Collie eye anomaly and useful vision therefore require no medical therapy simply for the underlying defect. Management focuses on monitoring vision and identifying complications that might benefit from specialist care.
Retinal detachment is the major vision-threatening complication. Whether treatment is possible depends on the type, extent and duration of the detachment. A veterinary ophthalmologist may discuss surgical or laser options in selected cases, but treatment cannot guarantee restoration of vision and some detachments are not repairable. Intraocular bleeding or secondary inflammation is managed according to the individual eye.
Dogs with reduced vision usually adapt well when their environment is predictable. Keeping furniture arrangements stable, using leads in unfamiliar places, blocking access to hazards and teaching verbal cues can help a partially sighted or blind dog remain confident. Eye protection from trauma is sensible for dogs with severe visual impairment.
Most dogs with mild choroidal hypoplasia require no treatment and live normally. Dogs with coloboma or retinal complications need periodic ophthalmic review so any haemorrhage, retinal detachment or secondary eye problem is recognised promptly rather than assuming the original defect is static.
Breeds or species affected
Australian shepherd
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Bearded collie
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Border Collie
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Boykin spaniel
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Collie
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Collie (rough & smooth)
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Lancashire heeler
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Longhaired whippet
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Nova Scotia duck tolling retriever
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Shetland sheepdog
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