03/04/2026
Pterygium in cattle refers to a wing-shaped fold of conjunctival tissue that grows from the inner corner (medial canthus) of the eye onto the cornea.
It is basically a fleshy membrane-like growth over the clear surface of the eye.
Structure involved
• Conjunctiva = pink membrane covering the white of the eye
• Cornea = transparent front part of the eye
In pterygium, the conjunctiva invades the cornea.
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How it looks in cattle
You may see:
• A triangular / wing-shaped pinkish-white tissue
• Starting from the medial side of the eye
• Extending toward the center of the cornea
• Sometimes associated with:
• watering
• mild irritation
• redness
• partial visual obstruction if large
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Cause in cattle
In cattle, a true pterygium is rarely described compared with other eye lesions.
When present, it may be related to:
• chronic irritation
• dust
• sunlight / UV exposure
• wind
• recurrent conjunctival inflammation
• old corneal/conjunctival injury
So it is basically a chronic proliferative conjunctival change.
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Pathogenesis (vet style)
Repeated irritation of the bulbar conjunctiva causes:
• fibrovascular proliferation
• migration of conjunctival tissue
• gradual extension over the corneal surface
This leads to a vascularized conjunctival fold covering part of the cornea.
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Clinical significance
Small lesions may cause only:
• mild epiphora
• irritation
• cosmetic defect
Large lesions may cause:
• corneal opacity
• visual interference
• chronic discomfort
