05/27/2026
Bone Scan and The Thoracic Spine
Nuclear scintigraphy (commonly referred to as bone scan) has great utility for evaluation of bony abnormalities throughout the spine in horses. These images show moderate radiopharmaceutical uptake in the regions of both the left and right articular processes of T18-L1 of a middle age warmblood gelding. Differentials for this degree of uptake include stress fracture or osteoarthritis.
Stress fractures of the vertebral column are relatively common in racehorses and patients can present with surprisingly mild clinical signs including poor performance and non-specific lameness issues. A study consisting of post-mortem evaluation of racing thoroughbreds revealed 50% of examined vertebral columns had evidence of previous stress fracture.
The location of uptake in the images of our patient was consistent with the articular process joint rather than the vertebral body itself. In horses, the lumbar spine is the least mobile segment of the spine. It is believed by some that the morphology of the joints in this segment of the spine allows absorption of excessive rotational torque which results in more pathology to the joints rather than vertebral bodies themselves. These forces can also cause formation of osteoarthropathy with or without a stress fracture and primary osteoarthropathy is another differential for the patient in our case.
Radiographs and/or ultrasonography are recommended for further assessment with treatment guided by the referring veterinarian. Repeat nuclear scintigraphy can be valuable to assess resolution or improvement.
Bonus fact: Can you guess what structure the blue arrow is pointing too? It is a kidney!