Neck pain, stiffness, and neurological impairments are the most common clinical problems that affect the horse’s neck and, ultimately, equine performance and welfare. Neurologic signs often arise from spinal cord or nerve root compression, which veterinarians generally have an easier time diagnosing. Identifying the underlying causes of neck pain and stiffness without neurological signs or limb lameness often poses challenges, however, so researchers set out to study these instances. 

Studying Neck Pathology in Horses

“We wanted to find out why horses had neck radiographs taken and what signs (they) were displaying,” said Yvette Nout-Lomas, DVM, PhD, associate professor of clinical sciences at Colorado State University’s College of Veterinary Medicine and Biomedical Sciences, in Fort Collins. “We also looked at the incidence frequency of transposition of the ventral lamina (which forms the bottom of the spinal canal, protecting the spinal cord and serving as an important muscle attachment component, which helps support the head and neck) of C6 to C7 (TC67) and what the final diagnosis was for all horses in our study.” Essentially, they studied how often the structural variation occurs where the lamina is missing from the underside of C6 and instead appears on C7. Horses with TC67 might present with clinical signs ranging from neck stiffness to bucking under saddle.

She said horse owners and equine veterinary practices are focusing more on neck pain and other neck disorders. “We have learned many things over the years regarding diagnostic imaging, vertebral column examinations, and development of undesired behaviors,” Nout-Lomas said. “For instance, undesired behaviors in horses under saddle almost always have a medical underlying cause that we need to look for, and this can sometimes be very difficult.”

TC67 is an anatomical variation horses have at birth, and it occurs more frequently in Warmblood breeds. Not all horses diagnosed with this condition develop problems, but some do, said Nout-Lomas. Therefore, researchers wanted to investigate previous literature to determine if these horses show signs of dysfunction more or less frequently than horses without the variation. “We know that not everything visible on imaging is necessarily correlated to neck pain or dysfunction,” she said. “For example, it is not uncommon for horses to have large articulations at the base of the neck that may be misinterpreted as arthritis.”

Findings and Practical Applications for Equine Neck Examinations

“We found no increase in neurologic disease or lameness in horses with TC67 compared to horses without this variation,” she said. “However, in the small number (27 of 135) of TC67 horses in our study, neck pain seemed to be more prevalent. The increased presence of pain in this group warrants further evaluation—for example, this was a retrospective study, and we were unable to determine whether TC67 was the actual cause of pain or whether other conditions such as osteoarthritic changes, perhaps, were present and the cause of pain.”

Nout-Lomas and her colleagues also noted that their work, similar to other published studies on this topic, does not show that lameness or neurological disease occurs more frequently in this group of horses.

The study findings do not support some ideas that all horses with TC67 have pathologies that cannot be resolved. “When horses are examined during prepurchase or for other veterinary reasons, it is critical that veterinarians become comfortable and experienced with neck and vertebral column examinations and incorporate assessments of mobility and pain in their examinations,” said Nout-Lomas. “This is a critical component of body position, carriage, and movement for the horse.” Some horses with neck pathology might not be limited in their performance.

Take-Home Message

Discomfort of any kind in horses often leads to undesirable or dangerous behaviors such as bolting, rearing, and bucking. Horse owners and veterinarians alike need to be able to identify pain-related horse behavior and respond appropriately. If owners suspect their horses are experiencing neck pain, they should reach out to their veterinarians for a thorough examination and diagnostic testing.

“It is gratifying … when you can find the source of (neck) pain, help the horse, and improve performance and horse/rider relationship,” said Nout-Lomas.