Nasal polyps are noncancerous growths that arise from the mucous membranes of the nasal cavity, nasal septum, or tooth socket. Polyps are usually single but can be multiple. They form in response to chronic inflammation by excess growth of the mucous membrane or fibrous connective tissue. They occur in all ages and breeds of horses.

Signs include poor airflow through the affected nasal passage, labored inhalation, a bad-smelling nasal discharge containing mucus and pus, and low-volume bleeding from the nose. The polyp may extend until it protrudes beyond the nostrils. Polyps are detected via endoscopic and radiographic examination, and microscopic evaluation of tissue samples provide a definitive diagnosis. They can be removed surgically.

Last full review/revision July 2011 by Bonnie R. Rush, DVM, MS, DACVIM; Neil W. Dyer, DVM, MS, DACVP; Joe Hauptman, DVM, MS, DACVS; Ned F. Kuehn, DVM, MS, DACVIM; Stuart M. Taylor, PhD, BVMS, MRCVS, DECVP; Wendy E. Vaala, VMD, DACVIM; Maureen H. Milne, BVMS, MVM, DCHP, MRCVS