Which statement accurately reflects the horse's vertebral formula?

Which statement accurately reflects the horse's vertebral formula?

• A. C7, T18, L6, Ca 15-21
• B. C7, T18, L6, Ca 14-20
• C. C7, T17, L6, Ca 15-21
• D. C8, T19, L6, Ca 15-21

Answer: (A)

In horses, the vertebral column has fixed counts in the neck and trunk, with the tail being variable. The neck always has seven vertebrae, the thoracic region typically has eighteen, and the lumbar region has six. The number of caudal (tail) vertebrae varies considerably among horses and can range roughly from about 15 to 21. Because of that variation, the commonly used vertebral formula for the horse is written as C7 T18 L6 Ca15-21. This aligns with the option you’re looking at. The other possibilities would change one of the fixed counts (for example, eight cervical vertebrae or seventeen thoracic vertebrae) or imply a tail count outside the usual range, which is why they don’t fit as well.

In horses, the vertebral column has fixed counts in the neck and trunk, with the tail being variable. The neck always has seven vertebrae, the thoracic region typically has eighteen, and the lumbar region has six. The number of caudal (tail) vertebrae varies considerably among horses and can range roughly from about 15 to 21. Because of that variation, the commonly used vertebral formula for the horse is written as C7 T18 L6 Ca15-21. This aligns with the option you’re looking at. The other possibilities would change one of the fixed counts (for example, eight cervical vertebrae or seventeen thoracic vertebrae) or imply a tail count outside the usual range, which is why they don’t fit as well.