The author generally uses topical and/or a combination of topical and systemic treatments, depending on the severity of the problem and the integrity of the tympanum. Because of the propensity of the cat to develop ototoxicity related to the use of various topical medications, some clinicians only use systemic therapies in managing otitis externa in the cat (i.e., oral glucocorticoids, antibiotics and/or anti-fungals). Therapy for a flare of allergic (usually atopic) otitis is directed at resolving secondary infections, reducing inflammation and removing debris from the ears. In the author's practice, atopic otitis externa is the most common cause of aural hematoma seen in the cat.ĭiagnosis is by history and rule out (e.g., seasonality rule out food sensitivity by restrictive diet trial). Secondary bacterial infections most commonly involve Staphylococcus pseudintermedius. The most common secondary infections are with Malassezia pachydermatis. Atopy or FS related otitis externa are usually bilateral, but may be predominantly or entirely unilateral. With atopy or FS, otic involvement may antedate the development of other cutaneous allergy signs, be concurrent with these signs, or may be the only clinical manifestation (i.e., ears the only area affected). In the author's practice, atopy related OE is significantly more common than that seen with food sensitivities. However, the incidence of both is significant and they tend to be under-diagnosed. The incidence of otitis seen in atopic and food sensitive cats is less than that seen in allergic dogs. Inflammatory polyps and middle ear neoplasms may also cause otitis media.Ītopy (Environmental Allergy) and Food Sensitivity (FS) Related Otitis Externa (OE) 1 In the author's experience, the fluid from affected ears is more commonly sterile but infection is possible. In one study, fluid within one (30%) or both (70%) middle ears was noticed as an incidental finding in 30% of cats with sinonasal disease. Occlusion of the Eustachian tube results in the accumulation of the secretions that are normally produced within the middle ear and is most commonly associated with chronic naso/pharyngeal disease (inflammation or neoplasia - lymphoma most common). Obstruction of the Eustachian tube may also be a significant predisposition to the development of otitis media. The tympanum is usually intact in such cases. This is seen more commonly than in dogs likely because of the greater incidence of posterior pharyngeal inflammatory disorders seen in cats (often viral in origin). Less commonly, otitis media may also arise from retrograde infections through the Eustachian tube. Perforation may be seen with debris accumulation, more aggressive bacterial infections (e.g., Pseudomonas sp.) or as a complication of masses growing within the ear canal (e.g., ceruminous cysts, ceruminous cystadenoma or cystadenocarcinoma, squamous cell carcinoma). Otitis media is most commonly seen as an extension from an otitis externa, through a perforated tympanum. Otitis media may be infectious (bacterial, fungal) or non infectious (polyps, neoplasia, foreign body). In the United States, the incidence with which feline otitis externa is diagnosed in general practice has increased by 34% since 2006 (Banfield Pet Hospital data 2011). They include bacteria, fungi (especially Malassezia spp.), ceruminous debris (e.g., ceruminoliths), proliferative changes, otitis media and treatment errors (e.g., over or under treatment or inappropriate treatment). Perpetuating factors are those that are capable of perpetuating the otitis even if the primary factor has been removed/resolved. Examples include immunocompromising infections (e.g., FIV) and masses in the ear.
Predisposing factors are those that make the ear more prone to the development of otitis externa. Other primary factors tend to be much less common and include foreign bodies, other ectoparasites ( Demodex, ticks), keratinization/lipid disorders (idiopathic ceruminous otitis), autoimmune diseases (e.g., pemphigus foliaceus) and masses (aural polyps, ceruminous cysts, neoplasia). The most common primary factors are ear mites ( Otodectes cynotis), with the next most commonly encountered being hypersensitivities (atopy, food sensitivity). Primary factors are those that are noted to cause inflammation in ears. The etiopathogenesis of otitis externa in the cat can generally be divided into various factors. Books & VINcyclopedia of Diseases (Formerly Associate)Įtiopathogenesis of Feline Otitis Externa and/or Otitis Media.VINcyclopedia of Diseases (Formerly Associate).
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