Microphthalmia in Texel lambs

AIM: To describe an outbreak of congenital microphthalmia in Texel lambs in New Zealand. 194 bedded whole by hand, trimmed and sectioned at various depths and stained with haematoxylin and eosin (H&E), Holme's silver and haematoxylin with and without luxol fast blue, and luxol fast blue alone. METHODS: Affected eyes were fixed in 10% formol saline, processed routinely for histopathology and stained with haematoxylin and eosin, Holme's silver and haematoxylin with and without luxol fast blue, and luxol fast blue alone. RESULTS: Macroscopically, the globes and optic nerves were hypoplastic. Histologically, all embryonic components of the eye were present, but the lens, ciliary body, iris and retina were dysplastic. Axons of the hypoplastic optic nerve were poorly myelinated. CONCLUSIONS: Congenital microphthalmia occurs in Texel sheep in New Zealand, and is likely inherited as an autosomal recessive trait.