Equine nasal cysts

Equine nasal cysts are epithelium lined, single or loculated cavities filled with fluid or pus. They normally form in the ventral concha, maxillary sinuses, and can extend down the nasal passages into the frontal sinuses.

Congenital forms have been previously described. Cysts in the sinus can be found in horses less than a year old, although rarely, but can also be seen in those 9 years and older.^[1] The clinical signs normally present as nasal discharge, facial swelling and in major cases, partial or total obstruction of the nasal airway can result.

Diagnosis

Radiographs generally provide better results than endoscopic examination when diagnosing these problems; multiloculated densities and fluid lines show up more readily in the sinuses, occasionally with dental displacement and also dental and jaw line distortion, flattened roots in the teeth, mineralization and soft tissue calcification, and major deviation of the septum and vomer bones.

Effects

If the head is placed in a downward position, the cyst will shift and liquids may come out and cause the throat to close up, which stops breathing. If this occurs press on the frontal cord in the throat with 2 fingers. Also very powerful stinging.

Treatment

Treatment involves radical surgical removal of the cyst and any of the involved lining of the concha – this would normally be tested by a laboratory, since there is a risk that some nasal cysts may be cancerous. In cases where such cancer shows in a removed nasal cyst, treatment can follow two courses. Radiotherapy is one, where the cancerous area is subjected to moderate doses of radiation, over a period of several weeks, with tissue testing being undertaken during the treatment. The other is via the administration of cytotoxic drugs, to travel through the bloodstream and attack the cancer cells.

Prognosis

If the cyst is benign, the prognosis for a complete recovery is extremely good, and the rate of any recurrence is minimal. Some horses may have a mild mucous discharge after surgery, which can be permanent, but this does not generally seem to cause problems. However, if the cyst does transpire to be malignant, the prognosis becomes worse, with roughly 70% survival, as opposed to a norm of more than 95% with benign cysts.

References