Primary Sinusitis

This is an infection of the horse’s sinus, similar to sinus infections experienced by people. These are usually caused by bacteria, but they can be caused by fungus. Additionally, an upper respiratory virus can predispose a horse to developing a primary sinusitis infection. Clinical signs include mucoid (white, green, or yellow) nasal discharge out of one or both nostrils, swelling or bulging of the facial bones, decreased appetite, lethargy and/or weight loss.

Paranasal sinus disease

Diagnostics

Radiographs of the skull, CT of the head (Gives the most diagnostic detail), Video endoscopy, Oral/dental exam, Sinoscopy.

Treatment

In acute cases the horse is usually medicated with systemic antibiotics and anti-inflammatory medication and re-evaluated in 2-4 weeks. If the sinus infection does not get better in this time frame, then surgical options need to be explored. One surgical option is to perform a procedure known as trephination, which involves drilling a hole that is approximately ¾ inch in diameter into the affected sinus with the horse sedated and standing. The puss within the sinus can then be flushed out using the trephine hole. In more severe cases a larger trephination hole or even a sinus flap is performed to allow instruments to be placed into the sinus and aid the removal of puss and other debris from the infected sinus. A sinus flap involves opening a flap of bone into the sinus that is 2-3 inches in width and 4-5 inches in length, which can be performed under general anesthesia or standing sedation depending on multiple factors. Fortunately, the horse’s face typically heals with minimal cosmetic defects no matter which surgical approach becomes necessary for management of the case.