Ocular findings in healthy newborn foals according to age

Summary The aim of this prospective observational clinical study was to carry out a descriptive ophthalmic investigation in healthy newborn foals for the establishment of normal ocular anomalies found during the whole neonatal period. To date there have been no studies specifically addressing the normal ocular findings and variations of the eye and adnexa in foals during the neonatal period. Knowledge of the ocular characteristics at this early age will help equine practitioners to better identify ocular abnormalities. A detailed ophthalmic examination was performed by boarded ophthalmologists on all admitted healthy newborn foals. There were 52 foals included in the study grouped into those that were 1-day-old, younger than 5 days, aged 6–15 days and 16–21 days. Menace response was found to be absent in foals younger than 15 days. Pupillary light reflexes were present in all foals but were slower and incomplete in 14/14 1-day-old foals (100%) and in 7/21 foals aged 2–5 days (33%). Palpebral reflexes were positive in all foals. Ventromedial strabismus was bilaterally present in 8/14 1-day-old foals (57%) and in 4/21 foals aged 2–5 days (19%). Conjunctival congestion was observed in all groups. Conjunctival haemorrhages, perilimbal vascular ring, lens suture opacities and multifocal tapetal haemorrhages were exclusive findings from 1-day-old foals, with an incidence of 36, 21, 36 and 29%, respectively. The means of IOP readings were similar in all age groups. Hyaloid artery remnant and optic nerve head congestion were present in all 1-day-old foals (100%), decreasing in incidence with age. Ocular findings in new neonates are different from those observed in older neonates and should be considered when examining the foal's eye. Findings described in this study will help equine practitioners to more accurately diagnose discrete or unusual pathological changes in the newborn foal's eye according to their age.