Maxillary Cysts

Introduction

Maxillary sinus cysts occur in horses. They originate in the maxillary sinus but can extend into all sinuses if not treated. Most are congenital.

Signalment

As they are mainly congenital, cysts are seen in horses less than one year of age. There is no breed or sex predilection.

Clinical Signs

There will often be a facial deformity depending on size of the cyst. If the cyst is small there may be no clinical signs at all. The horse may be observed to shake its head regularly and inspiratory noise may be heard on exercise.

Diagnosis

Sinus centesis will yield acellular yellow or pink fluid, which will become purulent if secondarily infected with bacteria.

On head radiographs, a mass may be noted in a sinus that is smooth in shape and appears non-invasive. There may be a decreased resonance of the image and fluid lines may be seen.

On endoscopy, there will be an axial deviation of the medial wall of the conchal sinuses and a pale, shiny, smooth surfaced mass may be seen; this is the cyst.

Treatment and Control

The cyst should be surgically removed by a frontonasal or maxillary sinusotomy. As it is non- invasive, the cyst usually separates easily from the sinuses via digital manipulation.

Prognosis

Good, and recurrence is rare.

References

Knottenbelt, D.C. A Handbook of Equine Medicine for Final Year Students, University of Liverpool.
Perkins, J (2008) Respiratory System Study Guide, Royal Veterinary College.

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