Outcomes after medical and surgical interventions in horses with temporohyoid osteoarthropathy.

Background: Temporohyoid osteoarthropathy (THO) is a cause of neurological disease in horses that is characterised by facial and vestibulocochlear nerve deficits. Studies reporting and comparing survival following medical or surgical treatment of THO are lacking.
Objectives: To compare survival and prognosis in horses with THO treated medically or surgically, and to report surgical complications.
Study Design: Retrospective study.
Methods: The medical records of horses diagnosed with THO were retrieved, and data on signalment, clinical signs and duration, corneal ulceration and bilateral occurrence were recorded. Neurological severity was graded according to clinical signs. Preoperative radiographic and endoscopic images were graded according to the severity of changes. Factors potentially affecting survival and treatment were compared using Cox proportional hazards regression.
Results: A total of 77 horses were identified as having THO during the period 1990-2014. Of these, 25 horses underwent ceratohyoid ostectomy (CHO) and eight underwent partial stylohyoid ostectomy (PSHO). Thirteen of 20, one of 25 and one of eight horses treated by medical therapy, CHO and PSHO, respectively, died or were subjected to euthanasia as a consequence of THO. Compared with CHO, medical therapy was significantly associated with nonsurvival, but there were no significant differences in survival between horses undergoing PSHO and medical therapy. The duration of clinical signs, and neurological, radiographic and endoscopic grades were not associated with survival of THO. However, the age of the horse was significantly associated with poorer survival. Survival time was significantly shorter in the medical therapy group compared with the two surgical groups combined, but did not differ significantly between the two surgical groups. No significant difference between groups was seen in the incidence of surgical complications (33.3% in the PSHO and 22.2% in the CHO group).
Main Limitations: This was a nonrandomised study of treatment effects on survival and included a low number of cases.
Conclusions: The survival prognosis in horses with THO is good to excellent in those submitted to surgical intervention, and fair in those treated with medical therapy alone.
(© 2017 EVJ Ltd.)