Aberrant conjunctival overgrowth in rabbits

14 Aberrant conjunctival overgrowth in rabbits


Aberrant conjunctival overgrowth, circumferential conjunctival hyperplasia and placation, epicorneal conjunctival membranes and pseudopterygium are all terms used to describe this abnormality. The condition is poorly understood and appears to be unique to the rabbit. The pink tissue is a fold of conjunctiva which grows centri-petally from the bulbar conjunctiva at the limbus to obscure the cornea. It remains attached at the limbus but the central fold of tissue is freely mobile over the corneal surface. Vision is maintained until the central circular ‘hole’ is occluded by the progression of the membrane. Histologically the lesion consists of normal conjunctiva lining both the inner and outer surfaces of the membrane and is thought to result from a focal excess of conjunctival collagen. Any breed of rabbit can be affected, but dwarf and dwarf-crosses might be predisposed.

A similar condition is seen in humans – pterygium – where a fold of conjunctiva grows across the cornea from the nasal limbus. It does become attached to the cornea, unlike in rabbits, and is more common in warm, dry, sunny climates and in certain ethnic groups, especially black people. Exposure to UV light, wind, dust and trauma predispose people to developing pterygium but none of these factors appears applicable to rabbits. It is postulated that local immunity factors are involved but no research has been undertaken to date to prove this.

Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Aberrant conjunctival overgrowth in rabbits

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