There are a number of complications that may arise for cats with ear infections or other causes of otitis that are either neglected or are not resolved successfully.
An Ear Hematoma May Occur as a Result of an Unresolved Ear Infection in a Cat
An ear hematoma, also sometimes called an auricular hematoma, is a pocket of blood that occurs in the flap of the ear. It will appear as a swollen ear flap.
Ear hematomas are frequent complications of untreated or unresolved ear infections. However, they can also occasionally occur without evidence of an ear infection.
Ceruminous Gland Hyperplasia, Cysts or Cancer Can Also Occur from Chronic Inflammation of the Feline Ear Canal
Ceruminous glands are structures that lie in the lining of the ear and ear canal. They are responsible, together with sebaceous glands, for secreting the wax that accumulates in the ears. They produce a substance that is helpful in maintaining the pH of the ear canal, helping to keep the ear canal healthy.
With chronic inflammation of the ear or ear canal, these ceruminous glands may become hyperplastic (thickened) or form cysts. These may appear as blue, brown or black "bumps" on the ear or inside of the ear canal.
It is possible for these hyperplastic or cystic glands to develop into tumors as well.
Invasion of the Middle and/or Inner Ear as a Complication of Ear Infections
Ear infections can also spread into the middle and/or inner ear and cause infection or inflammation there as well. This is somewhat rare in the cat but is known to occur.
Signs of a middle ear infection include paralysis of the facial nerve, deafness, keratoconjuncitivis sicca (KCS or "dry eye") and Horner's syndrome. (Horner's syndrome consists of drooping of the upper eyelid, prolapse of the third eyelid, recession of the eyeball and/or constriction of the pupil.)
Signs of an inner ear infection include vestibular disease, which results in a head tilt, loss of balance, incoordination and shifting eye movements known as nystagmus.
Learn more: Ear Infections in Dogs and Cats