Prevalence of hyoid injuries in dogs and cats undergoing computed tomography

- Computed tomographic (CT) images of the hyoid apparatus were examined in dogs and cats presented for unrelated conditions.
- Hyoid injury (fracture or luxation of the hyoid bones) was identified on computed tomography in 9/293 (3.1%) dogs.
- Of dogs with hyoid injury 7/9 (78%) had no history of trauma, dysphagia or dyspnea.
- No hyoid bone fractures or luxations were identified in 100 cats.
- Hyoid bone fracture or luxation may be an incidental finding in dogs.

Fractures of the hyoid bones have been reported occasionally in dogs, but the prevalence and significance of hyoid injury in dogs and cats are unknown. In human beings, hyoid injury is rare and usually is caused by direct trauma to the greater cornu, which are analogous to the paired canine and feline thyrohyoid bones. The aim of this study was to describe the prevalence and morphology of hyoid bone injury detected in dogs and cats undergoing computed tomography (CT) for unrelated disease. CT studies of 293 dogs and 100 cats from 2012 to 2016 were identified and reviewed retrospectively. Hyoid fracture (total of eight bones) or luxation (total of four sites) was present in 9/293 (3.1%) dogs, but none of the cats. One dog had bilateral fractures and one dog had bilateral luxations. The most frequently fractured bone was the epihyoid bone (4/8 fractures). Fracture margins were tapered and sclerotic, consistent with chronic non-union. There was no history of trauma, dysphagia or dyspnea in 7/9 dogs with hyoid fractures. Hyoid bone injury, particularly epihyoid bone fracture, may be an incidental finding in dogs.