SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
appear like SCC could be Habronema granulomas [especially on the palpebral
conjunctiva] and would not be suitable on PPE. Dermoids usually occur near the
dorsal limbus, can be haired and potentially a problem and are not suitable for PPE
whilst small, non-haired limbal dermoids would be considered suitable as they are
non-progressive. The dermoid could be removed and the horse presented again for
the PPE.
Cornea: This is probably the most commonly affected part of the equine eye and
may raise the most concerns about functional vision. The goal of the examiner here
is to identify lesions that may be congenital, could be permeant opacities or could be
progressive. Congenital leukomas (corneal opacities) can develop from a variety of
causes; however, because they are non-progressive, affected horses are generally
considered suitable for purchase by an informed owner. Affected animals would be
considered suitable if their central visual field is unaffected and in many
circumstances there may be axial opacities yet the animal has adapted well and is
functional. Acquired corneal scarring is also non progressive and can be assessed in
the same way. Corneal edema poses a problem. It is essential to establish if the
edema is endothelial in origin [fluorescein negative]. In most cases endothelial
edema is permanent and if extensive it is not suitable for PPE. Local edema may be
due to an intraocular mass or inflammatory exudate touching the endothelial layer.
This is unacceptable for the PPE. If edema is related to low grade inflammatory
pathology then re-assessment after treatment could be considered. The purchaser
should be advised that recurrence of the problem could occur. Linear keratopathy
(striate opacities in Descemet's membrane, which covers the inner surface of the
cornea) are incidental findings, and suitable for purchase. Note these are not Haab’s
striae associate with glaucoma!
Iris: Iris cysts typically don't affect purchase recommendations but the purchaser
should be advised that they may spontaneously increase in size or even break off
and potentially lodge and affect vison. Much the same advice is given for granulae
iridica cysts which are typically small enough to have little to no effect on horses'
vision, meaning affected animals are suitable for purchase. If the growths are large,
however, they are likely to obstruct the pupil's functionality. Iris hypoplasia or
heterochromia and iris coloboma in an otherwise normal globe are not considered
problems. Dorsal herniation and thinning of the iris is also of no significance. Anterior
segment dysgenesis, a combination of developmental anomalies in the anterior
chamber, generally don't affect a horse's purchase by an informed owner because
the lesions are typically non-progressive.
Probably one of the most difficult components of the pre-purchase examination is
identifying and interpreting lesions from previous uveitis episodes. These lesions
should be considered carefully. In all cases where there is evidence of previous
uveitis characterized by posterior synechiae, loss of granular iridica, cataracts,
pupilliary distortion, iris depigmentation, or pigment dispersal and iris
neovascularization, should be considered as unsuitable. An exception is when
evidence suggests traumatic causes like tearing of the iris. However affected horses
might be suitable for purchase by an informed owner if:
•
•
The lesions aren't extensive in nature;
They are only located in the anterior segment of the eye; and
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