Histologic Characterization of the Cat Middle Ear

Abstract

The purpose of this study was to establish microscopic normal in the middle ear of the cat while concurrently characterizing gross and microscopic lesions reflecting spontaneous otitis media. Both ears from 50 cats were examined grossly and processed for histologic examination of the external, middle, and internal ear on a single slide. Gross lesions of the middle ear were present in 14 of 100 (14%) and included turbid fluid, frank pus, hemorrhage, and fibrous thickening of the auricular mucoperiosteum. Histologically, 48 of 100 (48%) ears had evidence of ongoing or previous inflammatory middle ear disease, including proteinaceous fluid; vascular ectasia; expansion of the auricular mucoperiosteum by neutrophils, lymphocytes, and macrophages; cholesterol clefts; hemorrhage; fibrin; granulation tissue; membranous pseudo-glands; fibrosis; proliferation and/or osteolysis of the tympanic and septum bullae. Histologic lesions were identified in 34 of 100 ears (34%) lacking gross evidence of disease. Ears were classified histologically as either normal (52/100 [52%]) or diseased (48/100 [48%]). Diseased ears were further classified as mild to moderate (37/100 [37%]) or severely (11/100 [11%]) affected. Internal ear involvement was present in 11 of 100 (11%) ears. Histologic evidence of middle ear disease in cats is far greater than gross lesions or clinical literature suggests; further investigation and correlation of clinical and histologic disease are warranted. With minimal additional preparation, diagnostic specimens may be readily prepared and evaluated for this integral sensing organ.

Mucoperiosteal Exostoses in the Tympanic Bulla of African Lions (Panthera leo)

“…Moreover, their variable number, size, and shape could suggest different stages of bony proliferation of the TB in response to injury. 8,12 Sula et al 12 reported an active inflammatory infiltrate as well as extensive fibrosis of the auricular mucoperiosteum with or without bony proliferation, lysis, or remodeling in cats with chronic otitis media. Unfortunately, in the series of 8 lion skulls, the skeletonized condition of the samples restricted our histologic findings to the bone lesions but should encourage further investigations in postmortem studies of large felines.…”

“…Infectious (bacterial) otitis media has been more frequently described in dogs, cats, and cows. 7,12,13 Sula et al 12 recently described the histologic characteristics of diseased ears in a series of 50 cats and concluded that middle ear diseases in cats are far more common than gross lesions or clinical literature suggests.…”

“…2 Although the widespread use of CT imaging in dogs has facilitated their recognition, MpEs can be considered fairly uncommon, since they have been reported in very few dogs 2,3,14 and cats. 12 In the dog, MpEs can be associated with active signs of otitis externa or vestibular disease or can represent an incidental finding in dogs without signs of otitis media. The pathogenesis of MpEs remains undetermined; it has been suggested that they develop secondary to mineralization of necrotic debris from primary middle ear disease or otitis externa where the disease has resolved and the ear drum has healed.…”

Structural properties of the mastoid using image analysis and visualization

“…It should be noted that osteoneogenesis, formation of new bone, is also occurring during chronic middle ear infection as pointed by [12]. Such bone formation could result in the appearance of spicule pointing normal to the bone septae, as also illustrated in [75]. Fig.…”

“…Though cats have a bulla instead of a mastoid as in humans, Sula et al [75] reported the occasional formation of irregular bony spicules in cats with a history of chronically affected ears . Per Cayé-Thomasen et al [11] reported the formation of bone in the presence of a pathological bone, such as in chronic otitis media.…”