Van Bonn W, Montie E, Dennison S, Pussini N, Cook P, Greig D, Barakos J, Colegrove K, Gulland F
Veterinary Science Department, The Marine Mammal Center, Sausalito, California 94965, USA.
Dis Aquat Organ. 2011 Sep 9;96(2):89-96. doi: 10.3354/dao02376.
A yearling male California sea lion Zalophus californianus with hypermetric ataxia and bilateral negative menace reflexes was brought to The Marine Mammal Center, Sausalito, California, U.S.A., in late 2009 for medical assessment and treatment. The clinical signs were due to multiple gas bubbles within the cerebellum. These lesions were intraparenchymal, multifocal to coalescing, spherical to ovoid, and varied from 0.5 to 2.4 cm diameter. The gas composed 21.3% of the total cerebellum volume. Three rib fractures were also noted during diagnostic evaluation and were presumed to be associated with the gas bubbles in the brain. The progression of clinical signs and lesion appearance were monitored with magnetic resonance imaging, cognitive function testing and computed tomography. Gas filled voids in the cerebellum were filled with fluid on follow up images. Clinical signs resolved and the sea lion was released with a satellite tag attached. Post release the animal travelled approximately 75 km north and 80 km south of the release site and the tag recorded dives of over 150 m depth. The animal re-stranded 25 d following release and died of a subacute bronchopneumonia and pleuritis. This is the first instance of clinical injury due to gas bubble formation described in a living pinniped and the first sea lion with quantifiable cerebellar damage to take part in spatial learning and memory testing.
2009年末，一头患有运动过度共济失调和双侧阴性威胁反射的一岁雄性加州海狮（Zalophus californianus）被带到美国加利福尼亚州索萨利托的海洋哺乳动物中心进行医学评估和治疗。临床症状是由小脑内多个气泡引起的。这些病变位于脑实质内，多灶性至融合性，球形至卵形，直径从0.5厘米到2.4厘米不等。气体占小脑总体积的21.3%。在诊断评估过程中还发现了三根肋骨骨折，推测与脑内气泡有关。通过磁共振成像、认知功能测试和计算机断层扫描监测临床症状和病变外观的进展。随访图像显示小脑中充满气体的空洞被液体填充。临床症状消失，这头海狮带着卫星标签被放归。放归后，这只动物在放归地点以北约75公里和以南80公里处活动，标签记录到其潜水深度超过150米。这只动物在放归25天后再次搁浅，死于亚急性支气管肺炎和胸膜炎。这是有记录以来首例活体鳍足类动物因气泡形成导致临床损伤的病例，也是首例参与空间学习和记忆测试且小脑损伤可量化的海狮。
