胎儿期感染犬疱疹病毒所致者最多见。 原因不明的中枢神经系统先天性解剖学畸形。 以前曾认为与遗传因素有关，现已否定。
先天性畸形——小脑发育不全，眼缺陷，牛犊弱小。
Congenital abnormalities - cerebellar hypoplasia, ocular defects, weak small calves.
引起犬只小脑发育不全最常见的原因是宫内感染犬疱疹病毒。
The most common cause in dogs is an in utero infection with canine herpesvirus.
本病需与后颅窝蛛网膜囊肿、囊性新生物和变异的巨大枕大池以及重度小脑发育不全鉴别。
This disease should be differentiated from variation of the large cisterna magna arachnoid cyst of the posterior forssa cystic neoplasm and severe hypoplasia of the cerebellum.
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