A midsagittal centrum cleft of T5-6, malformation and fusion of T3-7,
intra- and extraspinal cyst, and myelodysplasia were found in a 3-mont
h-old female Arabian foal that had experienced posterior ataxia since
birth. Based on studies in other species, ecto-endodermal adhesions ea
rly in embryogenesis leading to formation of an enterogenous cyst is t
he most probable pathogenesis.