Page 695 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

670 CHAPTER 3

VetBooks.ir artery is harder to occlude distally by catheterisa- Prognosis
The prognosis is excellent if appropriate arterial
tion as there are numerous collateral branches.
The most important is the palatine artery, which
can be exposed in the mouth, caudal to the inci- occlusion is achieved in the absence of neurologi-
cal disease. Intraoperative complications are com-
sors immediately adjacent to the maxilla. It is not mon and warrant a guarded prognosis initially. The
recommended to simply ligate the external carotid prognosis for the return of neurological function is
and the palatine artery. This approach has been guarded. Many horses improve following resolution
reported to result in unilateral blindness. of the mycosis, but some deficits can remain. This is
of particular importance in performance horses that
3.127 present with RLN due to guttural pouch mycosis –
the prognosis for improvement here is guarded.

TEMPOROHYOID OSTEOARTHROPATHY

Definition/overview
This is a rare but increasingly recognised condition
involving bony proliferation and pain associated
with the temporohyoid articulation. The disease is
very variable in presentation.

Aetiology/pathophysiology
Fig. 3.127 A catheter is advanced 15 cm up the The precise cause of temporohyoid osteoarthropa-
internal carotid artery and the balloon of the catheter thy is not known. It has been postulated that the
inflated distal to the pouch. Distal and proximal to the condition is a septic arthritis of the temporohyoid
arteriotomy, the artery has been double ligated. joint following an extension of middle ear disease,
but there is no evidence of underlying middle ear
3.128 infection in most cases, although some horses do
have a history of prior ‘strangles’ infection. The
course of the disease is somewhat unpredictable, but
most horses are presented with an acute history. It is
suggested that ankylosis of the temporohyoid joint is
prevented by the constant movement of the stylohy-
oid bone via the tongue. This results in continuing
inflammation around the joint, and hence swelling
that can press on nerves adjacent to the joint, par-
ticularly the facial and vestibulocochlear. The move-
ment can also result in pathological fracture of the
basisphenoid bone.
Fig. 3.128 A horse
with temporohyoid Clinical presentation
osteoarthropathy, The clinical presentation is variable and clinical signs
showing drooping can include oral phase dysphagia, head shyness, non-
ear, drooping eyelid descript pain in the parotid area, difficulty in ridden
and left deviation of exercise, altered head carriage and reluctance to flex
the muzzle, typical the neck. A relatively consistent feature has been quite
of facial neuropathy. marked pain on squeezing the mandibles together,
The horse also has a leading to severe reaction from the horse. Facial neu-
corneal ulcer. ropathy is often quite marked (Fig. 3.128) and there