Outcomes following single, caudally based bilateral versus unilateral frontonasal sinusotomy for treatment of equine paranasal sinus disease.

Background: Bilateral sinus disease is relatively uncommon in horses, accounting for 3%-4.5% of horses with sinonasal disease, but may require bilateral paranasal surgery for complete resolution. Complications and recurrence following bilateral sinusotomy have not been reported or compared to those following unilateral procedures.

Objective: To describe clinical features and outcomes in horses undergoing standing single, caudally based bilateral frontonasal sinusotomy compared to unilateral frontonasal surgery.

Methods: Records of horses (n = 37) undergoing surgical treatment for sinus disease (five bilateral, 32 unilateral) were retrospectively reviewed (2010-2017) for signalment, presenting complaint, duration of signs preoperatively, diagnostic imaging, treatments administered, duration hospitalization, complications, and owner satisfaction with the procedure. Mann-Whitney testing was used to compare age, duration of hospitalization, and follow-up time in horses undergoing unilateral or bilateral procedures. Fisher's exact testing was used to determine if sex predilection was present for unilateral or bilateral disease. Survival time and time to recurrence were compared by Kaplan-Meier survival curves and log-rank curve comparison testing. Significance was assessed at p < 0.05.

Results: Length of signs prior to admission did not differ between horses with unilateral and bilateral disease (p = 0.09), but there was a tendency for horses with bilateral disease to have clinical signs for longer. Age (p = 0.19) and hospitalization duration (p = 0.53) did not differ between horses undergoing unilateral versus bilateral procedures. Recurrence or failure to resolve signs was reported in 11/32 (34%) of unilateral and 0/5 bilateral cases (p = 0.07).

Conclusions: The bilateral single, caudally based sinusotomy approach may be considered to effectively treat bilateral paranasal sinus disease without concern for increased risk of life-threatening complications or longer hospitalization duration than would be typical for unilateral sinusotomy procedures.