Bulla Osteotomy: When, How (Lateralversus Ventral, How Big?)

The tympanic cavity (epitympanum, mesotympanum, hypotympanum) represents a phylogenetic out-pouching of the upper respiratory system which communicates via the pharyngotympanic (Eustachian) tube with the pharynx and is situated between the external aural meatus and the inner ear (cochlear and vestibular) structures. The bony chambers are lined with epithelial components (cuboidal, squamous, columnar, ciliated, secretory) typical of the respiratory system. The cavity’s major role is the conduction of sound between the air/fluid interface of the outer and inner ears; the ossicles are an extremely efficient system for concentrating sound incident on the major tympanic membrane to the vestibular membrane. Additional, secondary functions include the provision for the drainage of cellular debris and mucus secretions and also the protection of the tympanic structures through barocontrol both of which occur via the pharyngotympanic tube.

Diseases necessitating surgical access to the tympanic chamber are common in both the dog and the cat. However, there are significant differences in the indications for this procedure between these species reflecting the major the difference in the pathophysiology of middle ear disease.

The Dog
The most common cause of middle ear disease (MED) in the dog is a secondary septic otitis media which develops as the consequence of longstanding inflammatory disease involving the external ear. In many cases conservative management with access through the disrupted tympanic and simultaneous management of the otitis externa is appropriate. However, definitive surgical therapy in this species is directed towards the removal of the primary aetiology (i.e. the external ear) and is most commonly achieved through total ear canal ablation (TECA), which also provides accompanying access for bulla toilet.  [...]