Deformations of the Cervical and Cranial Thoracic Vertebrae in a Bedridden Asian Elephant

GUNJI Megu, TAKAI Akira, ENDO Hideki

doi:10.5686/jjzwm.19.79

The present study reports an abnormality of the neck in a bedridden Asian elephant. When 1 year old, the elephant lost the ability to stand and grew up under the bedridden condition for 3.5 years. Our observations from CT scan revealed that the articular facets of the cervical and first 3 thoracic vertebrae possessed intricately rough surfaces and that the anterior articular processes of C4, C5 and C6 intruded to the adjacent processes. The articular processes were partly fused to the contiguous processes in the C5/C6 and T1/T2 zygapophyseal joints and the processes of C6 were completely coalesced with those of C7. The neck of the bedridden elephant was dorsally bent at 30.4 degrees more than that of a hyperostotic elephant. Under the bedridden condition, the nuchal ligament is contracted without the gravitational load of the head weight. This induces the dorsiflexion of the neck, and then generates a compressive force between adjacent vertebrae. The compressive force might cause the inflammation and bony destruction between the articular processes, and prompt the abnormal ossifications in the articulations through the repairing process. The abnormalities of the articular processes were identified in the attachment site of the nuchal ligament, and the vertebral fusions were distributed intensively on where the compressive force should be converged. This study concludes that a long-term lying posture under the bedridden condition might cause the over-dorsalization of the neck and the deformations of the articular processes in large mammals.

Deformations of the Cervical and Cranial Thoracic Vertebrae in a Bedridden Asian Elephant

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