Interpreting Imaging of Equine Neck – The Horse

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Neck pain in horses may be caused by a variety of conditions, including soft tissue (e.g. myofascial or synovial pain), neurologic or bony lesions. Kevin Haussler DVM, DC PhD Dipl. ACVSMR, Associate Professor at Colorado State University’s Orthopaedic Research Center in Fort Collins during his presentation at The American College of Veterinary Sports Medicine and Rehabilitation Symposium, held April 27-29, Charleston, South Carolina. Haussler’s presentation covered the anatomy of the cervical joints, the spectrum and severity of osteoarthritis in these spaces, as well as how to determine the clinical significance of imaging findings.

Osteoarthritis affects the entire synovial joint–that is, the two bones that meet at the joint and the cartilage, as well as the fluid and membrane within the synovial joint. Haussler said that it is a spectrum, because diagnostic imaging can detect some changes but not others. Diagnostic imaging can be difficult for veterinarians because of the complex anatomy of the cervical joint processes and the superimposition of structures.

Researchers have found that osseous changes are present in 50% of horses who are clinically normal. Horses often display a combination between normal and diseased articulations at the neck, Haussler explained. He said that radiographs are a two-dimensional way to diagnose a problem that is three-dimensional. This can make it difficult to establish a correct diagnosis. Some horses may experience severe pain or performance issues without any physical abnormalities being detected, while others may have significant bony anomalies that do not seem to cause pain.

Haussler said that in a study of 8 horses euthanized because of severe neck pain, investigators found that 86% of them had normal cervical radiographs. They found that only 3% of the horses had normal cervical anatomy, based on observed bone changes at necropsy.

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It is important to determine where bony changes occur. Veterinarians often use multiple diagnostic imaging modalities to get a complete picture of a horse’s anatomy. This includes computed tomography (CT), myelography (myelography), and ultrasonography.

The clinical relevance of imaging findings depends on the clinical signs, as well as the horse’s stiffness and pain. “When there is a combination of osseus and soft tissues changes, we must ask, ‘Which finding is most relevant?’ And ‘What should we do?'” said he.

Haussler says that when the clinical relevance of diagnostic imaging is unclear, veterinarians should consider the horse’s movement patterns, athletic usage, and overall performance in order to determine the appropriate treatment plan.