Inflammatory polyps (also called aural polyps, nasopharyngeal polyps, or oropharyngeal polyps) are growths or masses found in the ears, nose, and throat of cats.
Etiology and Pathophysiology of Inflammatory Polyps in Cats
Inflammatory polyps arise from the mucosal lining of the tympanic bulla, the pharyngeal mucosa, or the auditory tube. The exact etiological basis has yet to be fully elucidated; however, genetic, congenital, and infectious causes have been proposed. Inflammatory polyps are not neoplastic (ie, they are benign).
Although chronic upper respiratory inflammation (eg, with viral infections or chronic bacterial otitis media) has been thought to be a factor leading to the development of inflammatory polyps, a clear association with various bacterial (Mycoplasma spp, Bartonella spp, Chlamydophila felis) and viral (feline calicivirus, feline herpesvirus 1) infections has not been clearly demonstrated (1). Viruses such as feline calicivirus and feline herpesvirus 1 have not been identified in polyp tissue (2). There is no relationship with feline retrovirus status.
Inflammatory polyps can grow into the external ear canal, middle ear, nose, or nasopharynx.Clinical disease develops depending on the extent and location of the mass.
Epidemiology of Inflammatory Polyps in Cats
Inflammatory polyps occur most commonly in cats and rarely in dogs. There is an age predilection for juveniles or young adults (3 months to 5 years old). There is no sex or breed predilection.
Clinical Findings of Inflammatory Polyps in Cats
Inflammatory polyps appear as smooth, pink, fleshy, pedunculated masses (see polyp image).
Courtesy of Dr. Michelle Woodward.
Although some cats with middle ear polyps are subclinically affected, extension of the polyps can lead to otitis externa, otitis media, otitis interna, or nasopharyngitis.
Clinical signs of inflammatory polyps depend on the area of extension and are typically chronic and progressive.
Clinical signs of aural inflammatory polyps include the following:
head shaking
otorrhea
Horner syndrome (constricted pupil [miosis], elevated third eyelid, eye sunken into head [enophthalmos], and upper eyelid dropping [ptosis] on the affected side of the face)
head tilt
ataxia
nystagmus
circling
facial nerve paralysis
Clinical signs of nasopharyngeal inflammatory polyps include the following: nasal discharge, stertorous breathing, sneezing, dysphagia, and dyspnea.
Diagnosis of Inflammatory Polyps in Cats
Physical examination, including otoscopy
Radiography, CT, and MRI
Histological examination
Evaluation of cats for inflammatory polyps should include examination of both ear canals and the nasopharynx.
Diagnosis of aural polyps involves otoscopic examination of the horizontal canal. Purulent discharge from the bulla might need to be flushed and suctioned from the ear canal to visualize the polyp. Sedation or general anesthesia may be required.
The tympanic membrane can be intact if the polyp has not extended to the external ear.
Use of a video otoscope greatly facilitates visualization and treatment of polyps (see otoscopic image).
Courtesy of Dr. Jason Pieper.
Nasopharyngeal polyps originating from the eustachian tube can be visualized by retracting the soft palate rostrally.
Radiography of the bullae can reveal opacities in affected bullae.
CT or MRI can be helpful if a mass is suspected in the tympanic bulla, which cannot be visualized with an otoscope.
Definitive diagnosis is based on histological examination.
Treatment of Inflammatory Polyps in Cats
Surgery
Steroids
Antimicrobials
There are both minimally invasive and surgical techniques to remove inflammatory polyps.
For polyps that extend into the external ear canal or under the soft palate, the simplest technique is traction avulsion, which might have a lower recurrence rate if performed with a lateral approach and if the stalk is removed.
Although traction avulsion is a reasonable first-line approach, ventral bulla osteotomy is considered the treatment of choice by some surgeons.
In cats with chronic otitis and subsequent stenosis of the horizontal ear canal, ventral bulla osteotomy might be the only way to approach the mass.
Incomplete removal of the base of the polyp by traction avulsion alone leads to rapid regrowth and return of clinical signs in 15–50% of cats. Administration of topical steroids in the bulla for 30–45 days seems to slow this regrowth.
Systemic antimicrobial treatment is also indicated, based on the culture of material removed from the bulla during surgery.
Key Points
Clinical signs of aural polyps range from ear scratching, head shaking, and otorrhea to Horner syndrome, head tilt, ataxia, and nystagmus.
Clinical signs of nasopharyngeal polyps range from nasal or ocular discharge, stertorous breathing, and sneezing to dysphagia or dyspnea.
Diagnosis can be based on examination of the ear canals and nasopharynx or might require advanced imaging.
Treatment is removal of the polyp.
For More Information
Anderson DM, Robinson RK, White RAS. Management of inflammatory polyps in 37 cats. Vet Record. 2000;147(24):684-687.
Schuldenfrei MD, Lam ATH, Outerbridge CA, White SD, Affolter VK. Evaluation of aural masses submitted as inflammatory polyps in 20 dogs (2000–2020). Vet Dermatol. 2023;34(1):77-86.
Also see pet owner content regarding nasopharyngeal polyps in cats.
References
Klose TC, MacPhail CM, Schultheiss PC, Rosychuk RA, Hawley JR, Lappin MR. Prevalence of select infectious agents in inflammatory aural and nasopharyngeal polyps from client-owned cats. J Feline Med Surg. 2010;12(10):769-774. doi:10.1016/j.jfms.2010.05.013
Veir JK, Lappin MR, Foley JE, Getzy DM. Feline inflammatory polyps: historical, clinical, and PCR findings for feline calici virus and feline herpes virus-1 in 28 cases. J Feline Med Surg. 2002;4(4):195-199. doi:10.1053/jfms.2002.0172
