Occipitoatlantoaxial malformation with duplication of the atlas and axis in a half Arabian foal.

This study looks at a rare congenital malformation called occipitoatlantoaxial malformation which is observed in a half Arabian foal. The abnormal formation involved the duplication of atlas and axis bones which led to cervical spinal cord compression and subsequent inability of the foal to stand post-birth.

Introduction to the Malformation

• The research presents a case study about a 2-week old half Arabian foal with a rare form of congenital malformation named occipitoatlantoaxial malformation.
• This is an atypical form of the malformation where there is a duplication of atlas (the first cervical vertebra) and axis (the second cervical vertebra).
• Due to this malformation, the newborn foal exhibited symptoms of spastic tetraparesis, a symptom that may include muscle stiffness, spasms, and functional impairment in all four limbs.

Details on the Malformation in the Case Study

• Upon further analysis of the foal’s bone structure, it was discovered that the malformation was such that there were two atlases present in the foal instead of one.
• One of these atlases was joined to the occipital bones which are located at the back portion of the skull, while the other atlas formed a joint with the first atlas and an axis.
• The axis bore a peculiar long projection, known as dens, which projected into the vertebral canal – the hollow part of the spinal column containing the spinal cord.

Further Findings from the Examination

• Going beyond the malformation, the researchers also took note of the ossification centers of the foal’s axis which indicated a partial duplication of the bone.
• Ossification centers are the areas of the body where bone formation takes place. In this case, detection of partial duplication signifies an anomaly in regular bone growth and development in the foal, suggesting a genetic or developmental disorder.