Page 791 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

766 CHAPTER 4

VetBooks.ir surgically, with the intention to repair the damaged can be performed in the standing horse, gives a
Persistent salivary duct fistulae can be treated
three-dimensional appraisal and enables more accu-
duct. The duct is approached by surgically debriding
the fistula and dissecting down to the duct. A thin rate and precise surgical planning (Fig. 4.92).
salivary catheter is passed caudad towards the gland Differential diagnosis
and rostrad towards the salivary papillae in the oral Parotiditis, parotid melanoma, retropharyngeal
cavity. The duct is then sutured with fine absorb- or submandibular lymphadenitis, guttural pouch
able material (5-0 polydioxanone or polyglactin). enlargement.
The end emerging from the papilla is sutured to the
cheek and the tube left in situ as a stent for 3 weeks. Management
A simple surgical solution is to ligate the sali- The calculus can be freed by incising the buccal
vary duct proximal to the fistula. Unless salivary mucosa via an oral approach in the sedated horse,
flow is re-established partial atrophy of the gland or alternatively via an external transcutaneous
follows. Sclerosis of the duct by curetting and inject- approach. The sialolith is expressed into the oral
ing it with iodine solution has also been suggested cavity and the duct heals by granulation. A more
to achieve occlusion of the duct. Preferred scleros- technically difficult approach is to incise the skin
ing agents include 10% buffered formalin, which is and duct over the calculus after local desensitisation,
injected and kept in contact for 1–2 minutes. Other and subsequently meticulously to close the duct with
agents have been used, but with more serious side- fine sutures, after ensuring the distal portion to be
effects, including facial oedema. patent. Postoperatively, cannulation of the salivary
Trauma to the sublingual glands can result in a duct, via the oral papilla, for a few days helps prevent
sublingual salivary mucocoele. These lesions, which closure. The cannula can be tunnelled externally
are located lateral to the frenulum, can easily be
treated by marsupialisation into the oral cavity.
4.92
SALIVARY GLAND CALCULI
(SIALOLITHS)

Definition/overview
Precipitations of mineralised material within the
salivary glands or ducts.

Aetiology/pathogenesis
Salivary calculi are rare in horses and are only of clin-
ical significance if they become lodged in the salivary
papilla at the orifice of the parotid salivary duct. The
calculi consist of calcium carbonate and sloughed
cells and can reach several centimetres in size.

Clinical presentation
Distension of the duct proximal to the calculus may
be detected by palpation or ultrasonographically.

Diagnosis
Salivary calculi are often radiopaque and therefore
visible on plain radiographs. Ultrasonography may
reveal hyperechoic matter within the parenchyma of Fig. 4.92 3D bone algorithm reconstruction of a horse
the salivary glands or within the ducts. CT, which with a salivary calculus obstructing the parotid duct.