Page 258 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.6 The hea d 233

VetBooks.ir 1.441 1.442

Fig. 1.441 Endoscopic view of the guttural pouch Fig. 1.442 CT cross-sectional reconstruction
of a horse with tympanohyoid osteopathy showing showing changes in the left temporohyoid articulation
enlargement of the proximal region of the stylohyoid associated with osteoarthropathy (temporohyhoid
bone (arrow). Radiography also revealed marked osteoarthropathy).
thickening of the tympanic bulla.

Differential diagnosis Anti-inflammatory drugs are also useful to alleviate
The condition must be differentiated from other pain and inflammation and in some cases a conserva-
causes of CN disease. tive approach alone may be successful. Partial stylo-
hyoidectomy, to decrease the force on the ankylosed
Diagnosis temporohyoid joint and prevent fracture, has been
Osseous enlargement of the proximal aspect of the superseded by the ceratohyoidectomy procedure.
stylohyoid bone or sclerosis of the tympanic bulla This technique appears to reduce the risks associated
may be diagnosed radiographically, but endoscopy with stylohyoidectomy, which include dysphagia,
of the guttural pouch has proved more consistently hypoglossal nerve damage and repeat ankylosis with
successful (Fig. 1.441). CT examination, however, the remains of the stylohyoid bone.
allows determination of the extent of the osseous
proliferation of the affected stylohyoid bone and/ TEMPOROMANDIBULAR JOINT DISEASE
or the temporohyoid articulation (Fig. 1.442). Soft
tissue and osseous changes in the middle and inner Definition/overview
ear can also be detected using CT, giving important Disease of the temporomandibular joint (TMJ) is
aetiopathogenic and management information. In uncommon, with occasional case reports of osteoar-
many institutions, CT can be performed with the thritis (OA), septic arthritis and luxation.
horse standing, which is particularly useful in cases
afflicted with neurological signs that may compro- Aetiology/pathophysiology
mise safe recovery from general anaesthesia. The TMJ forms the articulation between the
mandibular condyle and the zygomatic process
Management of the temporal bone. It is divided into two main
Even without CT diagnosis of an obvious ear infec- compartments by a fibrocartilaginous meniscus
tion at the time of presentation, antimicrobial ther- (or disk). OA of the TMJ can be seen in horses
apy should nevertheless be initiated as a precaution. with chronic and severe dental abnormalities, but