Author: Sharon May-Davis Published: Journal of Equine Veterinary Science 34 (2014) 1313- 1317
Full title: “The Occurrence of a Congenital Malformation in the 6 th and 7th Cervical Vertebrae predominately observed in Thoroughbred Horses.”
Abstract (click on the link above to download full article): During the dissection and skeletal examination of 123 horses, it was observed that a significant number had a gross skeletal congenital malformation of the 6 th and 7 th cervical vertebrae. In the 6th cervical vertebra (C6), either a unilateral or bilateral absence of the caudal ventral tubercle (CVT) was noted. In the presence of the C6 malformation, the 7th cervical vertebra (C7) presented either as normal, or, with a unilateral or bilateral transposition of the CVT from C6 onto the ventral surface of C7 with an arterial foramen. This transposition onto C7 was noted to be present on the corresponding side as the absent CVT on C6. Of the 123 horses examined, the congenital malformation of C6 was noted in 19 of 50 Thoroughbred horses; 3 of 3 Thoroughbred derivative horses; 1 of 15 non-descript bred horses and 0 of 55 purpose bred horses of mixed breeds. In total, 23 horses expressed a C6 congenital malformation of which, 22 were Thoroughbreds or Thoroughbred derivatives. Of these 22 Thoroughbred and Thoroughbred derivative horses, 11 of 22 expressed either a unilateral or bilateral transposition of the CVT from C6 onto the ventral surface of C7 with an arterial foramen on the corresponding side. This malformation could have functional and clinical ramifications in the postural and locomotive properties of the equine neck and cervicothoracic junction as reported in other species.