Salivary Fistula

Description

A salivary fistula can result from injury to any salivary gland, but most commonly the parotid. Fistulas forming from other glands is uncommon. Damage may be due to traumatic wound to the face e.g. bite wound or abscess drainage. Exopthalmus is the most likely cause of zygomatic fistula. The continuous flow of saliva due to trauma to the face prevents healing and therefore a fistula develops. Discharge from the gland may be noticeably worse before or during feeding.

Diagnosis

Diagnosis is largely made from clinical signs and history.

The fistula is often visible over the parotid region, or located upon clinical examination. Discharge from the fistula, which must be differentiated from a draining sinus, often results in a visibly wet face. The salivary discharge from a fistula is usually golden or blood tinged saliva, which will be viscous and 'stringy' in appearance. The presence of mucous can be confirmed by using periodic acid-schiff stain if necessary.

History of or current presence of a wound over the parotid regionis a very good indicator.

Treatment

Surgical ligation of the duct proximal to the injury will usually resolve the problem. Complete removal of the gland can be performed if necessary. However, removal of the parotid gland is not usually performed due to the high risk of complications such as cranial nerve trauma.

The skin is incised over the duct on the side of thebface (beware of buccal nerves) and a wide diameter suture material can be used to cannulate the duct in order to aid locating it during surgery.

Occasionally a mucocele may develop from the site of surgery.

References

Ettinger, S.J., Feldman E.C. (2000) Textbook of Veterinary Internal Medicine 5 th Ed

Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier
Merck & Co (2008) The Merck Veterinary Manual