Chronic Ear Infections in Cats
Overview of Chronic Ear Infections in Cats
Otitis is an inflammation of the ear and it is one of the most frequent reasons for owners to seek a veterinarian’s help. The prevalence of otitis externa, or inflammation of the external ear, in cats has been reported to be between 10 to 20 percent although in more tropical climates it is probably closer to 30 to 40 percent.
The term otitis does not refer to a specific disease, but it is a symptom of many diseases and not a specific diagnosis.
Causes Allergies, such as inhalant allergy and food allergy Parasites such as ear mites Endocrine diseases such as hypothyroidism Auto-immune diseases like lupus Tumors
Chronic inflammation stimulates the proliferation of the skin lining the ear canal. As a consequence, thickening of the canal occurs and leads to narrowing of the canal. More importantly the skin is thrown into numerous folds, and this inhibits effective cleaning and the application of medications. These folds act as a site for the perpetuation and protection of secondary micro-organisms like bacteria.
Inflammation of the middle ear (otitis media) results from chronic inflammation of the external part of the ear canal, rupture of the ear drum and establishment of infection in the middle part of the ear. Discharge in the tympanic cavity is difficult to treat with topical therapy and often remains as a source for infection. Otitis media is usually bacterial in origin. Clinical signs suggestive of otitis media include head shyness and pain on palpation of the ears. Some cases of otitis media might experience head tilt, circling and dry eyes, but the vast majority do not have neurological abnormalities.
As the ear drum quickly grows back after rupture, otitis media may also be present, even if an intact membrane is seen on otoscopic examination. Radiography cannot be used to completely rule out the presence of otitis media since 25 percent of confirmed cases had no radiographic evidence of the disease. In one study, otitis media was present in 80 percent of cases of chronic, relapsing otitis externa, so it must be considered as a possible cause of any refractory or relapsing otitis externa. Treatment of otitis media is based on bacterial culture and sensitivity results. Most cases require long term antibiotic therapy, a minimum of 2 months, and aggressive topical therapy.
Diagnosis of Chronic Ear Problems in Cats
The identification of the underlying disease responsible for the chronic ear disease is of crucial importance. In order to do this it is important for your veterinarian to: Take a complete history that includes information concerning the age of onset, progression of the disease, and response to previous treatments. Perform a thorough physical examination of the ears to detect the presence and condition of tympanic membrane, the severity of changes in the ear canal, and also the rest of the body to detect signs of concurrent skin or internal disease Examine the ear discharge under the microscope to identify the organisms that are perpetuating the infection. Bacterial culture may be necessary in cases that have been treated by numerous drugs with only moderate improvement, because some of the bacteria tend to become rapidly resistant to commonly used antibiotics.
Treatment of Chronic Ear Problems in Cats Treat the secondary infections aggressively. Antibiotics and antifungal drugs may be prescribed for extended periods of time, up to two months, in cases in which the infection has progressed in the deep part of the ear canal (otitis media). This happens in over 80 percent of cases of animals with chronic ear disease. Thoroughly clean the ear canals. Topical therapy is vitally important for successful management of otitis. Ear flushing under sedation or general anesthesia is required in most cases to remove the discharge that is present in the deep part of the ear (bulla). Failure to remove this material will result in poor response to treatment and relapse of infection as soon as therapy is discontinued. Wax, oil, and cellular debris may be irritating, prevent medication from contacting the canal epithelium, and produce a favorable environment for microorganisms to proliferate and inactivate certain antibiotics.
Regular cleaning at home is an important part of the therapy. Several products can be used. A mixture of vinegar and water (1/10) is a good degreasing solution to remove wax (cerumen) and dry the excessive moisture in the ear canal. The liquid should be applied gently in the canal, the ear massaged to allow breakage of the cerumen and cotton balls used to remove the cerumen and wipe out the excess liquid. Extreme care should be used when mechanically cleaning the ears. The use of cotton applicators should be avoided or limited as they may cause rupture of the tympanic membrane. Also powders should not be applied in the canal as they build up, predisposing the ears to the development of secondary infections. Several products are available on the market and they should be used as directed by a veterinarian as some of them may interfere with the efficacy of the topical medications. These products are usually classified as either ceruminolytic or drying agents. Gentle massage improves their effect. Most of these products are contraindicated with a ruptured ear drum. However, frequently the condition of the ear drum cannot be determined until after the canal has been cleaned. In those cases the probability of ear toxicity may be decreased by flushing with water after the application of such agents.