Diagnosis and surgical treatment of cystlike lesions of the equine paranasal sinuses.

Development of cysts in the equine paranasal sinuses is probably a congenital disease; however, signs may not appear for several years. In 4 cases, clinical signs were observed when fluid accumulation within the cysts resulted in nasal discharge or facial swelling, or when secondary infection occurred. Treatment required surgical removal of the lining membrane and other involved tissues. Postoperative care included lavage of the sinuses and systemic antibiotic therapy.