Narrowing of the equine cervicothoracic intervertebral foramina (IF) has the potential to cause forelimb lameness and/or neck pain although limited information is available on CT of the IF. The aims of this retrospective, analytical study were to describe a protocol for quantifying CT cervicothoracic IF size; evaluate the repeatability of IF size measures; test associations between IF size and adjacent articular process (AP) size, ventral extent, and anatomic location; and determine the proportion of IF with narrowing. Computed tomographic images were acquired in 20 Warmblood horses that presented with forelimb lameness and/or neck pain. All IF between C5 and T2 (n = 160) were evaluated. IF cross-sectional area (CSA), APCSA, and AP ventral extent were measured. The repeatability of IFCSA measurement was calculated. Possible associations between IFCSA and: APCSA, ventral extent, side, or location were assessed. IF narrowing was defined as more than 50% of reduction in IF height when compared with its widest part(s). The repeatability of IFCSA measurement was excellent. There was a significant association between IFCSA and: APCSA (P < 0.001; R2 = 0.859; slope = -0.106), ventral extent (P = 0.022; R2 = 0.161; slope = -0.0617), and location (P < 0.001; higher values between C7 and T2). The association between IFCSA and ventral extent was small. Narrowing was identified in 61 (38.1%) IF. Maximum degree of narrowing was most common at the cranial (26.3%) and middle (68.8%) third of the IF. Narrowing was not identified at T1-T2. In conclusion, CT cervicothoracic IF size can be measured with excellent repeatability, and associations were found between IF size and: AP size, ventral extent, and location.
Keywords: cervical; computed tomography; horse.
© 2022 American College of Veterinary Radiology.