The Computed Tomographic Appearance of Equine Temporohyoid Osteoarthropathy

Abstract

Equine temporohyoid osteoarthropathy is characterized by progressive osseous proliferation of the temporohyoid articulation and surrounding structures. The diagnosis has generally been made using radiography and endoscopy of the guttural pouch. Recently, computed tomography (CT) has been used in the diagnosis of temporohyoid osteoarthropathy. This study was performed to determine the CT imaging characteristics of temporohyoid osteoarthropathy and to compare these to radiographic and endoscopic findings. CT scans from 16 horses with a final diagnosis of temporohyoid osteoarthropathy were reviewed. Five horses that had undergone CT scan for reasons other than temporohyoid osteoarthropathy were included as controls. Qualitative and quantitative data were used to describe the magnitude of the CT findings. Osseous proliferation of the stylohyoid bone and temporohyoid articulation was found to be a consistent feature of temporohyoid osteoarthropathy. Thickening of the ceratohyoid bone and proliferation of its articulation with the stylohyoid bone was frequently identified and this finding may have surgical implications. Horses with neurologic deficits had increased stylohyoid width that was significantly different than the subclinically affected side. CT evaluation also allowed the identification of subclinical bilateral disease in horses thought to be unilaterally affected based on clinical examination.

Temporohyoid osteoarthropathy in the horse

“…There are different aetiopathogeneses for THO in the horse resulting in similar clinical and imaging manifestations (Hilton et al . ).…”

“…; Hilton et al . ). Stylohyoid bone enlargement is presumed to occur from the immobility associated with ankylosis of the temporohyoid articulation and subsequent lack of bony remodelling (Divers et al .…”

“…It has been mentioned elsewhere that ceratohyoidectomy may be performed bilaterally and prophylactically on the contralateral side, but detailed information and case follow‐up have not been published (Hilton et al . ).…”

“…Computed tomography is also more accurate for the detection of fractures or concurrent middle ear disease (Hilton et al . ; Palus et al . ).…”

“…Although the natural progression of the disease is unknown, it is thought to be a slowly progressive entity (Hilton et al . ; Naylor et al . ).…”