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Aniridia in a Thoroughbred horse
Author(s) -
UEDA Y.
Publication year - 1990
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.1990.tb04707.x
Subject(s) - photophobia , foal , aniridia , ciliary body , ophthalmology , cornea , medicine , anatomy , iris (biosensor) , mydriasis , gonioscopy , biology , glaucoma , biochemistry , genetics , computer security , computer science , biometrics , gene
Summary Aniridia presents with very characteristic typical signs and has been reported in man (Newell and Ernest 1974), calves (Saunders and Fincher 1951) and horses (Ericksson 1955; Joyce 1983). This case report records aniridia in a Thoroughbred. The animal, a two‐month‐old brown colt, presented with a history of unusual brightness in both eyes and strange behaviour. Clinical examination revealed curtain‐like pigmentation in the upper part of the cornea from the superior limbus which was thickened and poorly demarcated. Some vascularisation was present in the affected corneal region. The iris was absent and the tips of the ciliary body processes were apparent around the lens equator. A small central cataract was present. Intraocular pressure was normal and there were no abnormalities detected on ophthalmoscopic examination of the fundus (Fig 1). The condition was bilateral. Examinations at three and five years of age revealed no further abnormalities. The colt was well developed from birth and although behaving as the other colts, photophobia was evident in the paddock at all times. The horse was quiet in the stable and would sometimes stare in one direction for long periods. It was nervous outside; training was carried out in the early morning as the animal exhibited certain wild behaviour in bright sunshine and reacted sharply to reflected light from pools of water. However, it was placed first on four occasions, second on five occasions and third on one occasion from 37 starts. The colt was gelded at 16 months and was the eighth foal from a mare imported from Ireland; none of the other offspring were affected and the mare showed no evidence of illness during pregnancy.