How to: Manage Temporohyoid Osteoarthropathy

Disease background
Temporohyoid osteoarthropathy (THO) is an uncommon condition of horses affecting the stylohyoid and petrous temporal bones and the temporohyoid joint. Osseous proliferation, degenerative joint changes and ankylosis of the joint develop, compromising normal movement. While the condition may be clinically silent or associated with nonspecific signs, signs of cranial nerve dysfunction result from fracture of the petrous temporal bone and/or stylohyoid bone subsequent to abnormal biomechanical forces with movement of the tongue/head. The neurological dysfunction presents challenges for treatment and management of affected horses. Furthermore, prevention of neurological disease or management for non-neurological manifestations in horses with THO may be goals of treatment.

The aetiopathogenesis of THO is unknown, although otitis media-interna from local or haematogenous spread of bacteria, nonseptic degenerative arthrosis of the temporohyoid (TH) articulation or traumatic injury to the TH region have been proposed (Divers et al. 2006). The disease is most commonly diagnosed in middle-aged horses, although younger animals may be affected (Readford et al. 2013). [...]