Evaluating Ultrasound as a Noninvasive Technique for Investigating Anatomical Variations of the Equine Nuchal Ligament Lamellae.

Ultrasound is a well-established modality in equine investigative and diagnostic procedures. Although to date, it has not been utilized in examining the attachments of the equine nuchal ligament lamellae (NLL) onto the cervical vertebrae, for which a noninvasive technique is currently lacking. This study presents a standardized methodology for investigating the equine NLL using ultrasonography, and further evaluates the ultrasound images against postmortem dissection in two nonrelated horses. The ultrasound images in both horses clearly presented the attachment points of the NLL to the dorsal spines of the cervical vertebrae from C2 to C5, whereas no attachment points could be seen from C6 to C7. The ultrasound images were confirmed through close, comparative inspection of the NLL postmortem. Therefore, ultrasound provides a noninvasive alternative to gross anatomic dissections for investigating the NLL attachments in members of the family Equidae. Importantly, this provides an opportunity to examine endangered breeds or isolated populations without the detrimental loss to the gene pool of rare anatomic and or primitive traits.