Acute or chronic inflammation of the epithelium cells in the ear canal. It is characterized by increased discharges and varying degrees of pain and pruritis. It is the most common disease of the ear canal in dogs and cats and can have many contributing factor to its cause.
The causes of otitis externa have been grouped into 3 areas. Primary factors are disease conditions that directly cause the otitis. Predisposing factors are conditions that place an individual at risk for developing otitis. Perpetuating factors tend to prevent the resolution of the otitis once it develops. Often all 3 factors are involved, but each category must be identified and addressed separately. In this way a more accurate prognosis can be provided, a specific and safe therapeutic plan formulated, and the best possible outcome from treatment assured.
Primary factors include parasites ( Otodectes , Psoroptes , Sarcoptes , Demodex spp ), foreign bodies (grass awn, concreted wax, medications), tumors (cerumin gland adenoma, inflammatory polyps), hypersensitivity (atopy, food sensitivity, contact dermatitis), disorders of keratinization, hypothyroidism, autoimmune diseases, juvenile cellulitis, and irritants (cleaners, plucking fur, etc).
Predisposing factors are often congenital or environmental and include conformation (pinnal carriage, narrow ear canal, excessive hair or ceruminous glands), maceration of the ear canal from overtreatment or swimmer’s ear, and systemic disease. Small changes in the otic microclimate may alter the delicate balance of normal secretions and microflora and result in opportunistic infections. Any disease that affects normal responses to pathogens can predispose the ear canal to opportunistic infections.
Perpetuating factors include bacteria, yeasts, otitis media, and progressive pathologic changes. Once the environment of the ear canal has been altered by a combination of primary and predisposing factors, opportunistic infections and pathologic changes occur, which prevent resolution of the disease. Chronic pathologic changes in the ears may also reflect a generalized systemic or skin disease. Unless all the causes are identified and treated, recurrence may be expected.
signs and symptoms:
Rubbing ears along the ground or furnture
Brown discharge from the ear canal
Ears are painful to touch, may cry or whimper
Skin in ears are red and warm to touch