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Chronic otitis is basically a long-lasting ear infection that can affect any cat, causing itchy, painful ears. Quite a few things can cause the disease — parasites, allergies, growths, and more — which is progressive and can lead to rupture of the eardrum or even permanent narrowing of the ear canal. Treatment starts with cleaning the ear and using medications like antimicrobials and anti-inflammatories. However, in some cases, surgery may be the best option.
Chronic otitis is a disease of the ear canal of cats. Otitis can be classified as externa (of the outer ear canal alone), media (involving the middle ear), or interna (involving the inner ear and associated structures).
Unlike the typical ear infections humans suffer (children, especially) in which the middle ear is affected, this disease is one that affects the external ear canal primarily and the middle and inner ear secondarily. As such, this disease is categorized as a dermatologic (skin-related) condition.
The typical disease process is as follows: Irritation to the skin lining the ear canal causes inflammation, which results in excess wax production and a comfortable environment for yeast and bacteria (normal residents of the ear canal) to overgrow. These microbes cause significant itchiness and more inflammation, which leads to an itch-scratch cycle conducive to self-trauma via headshaking, scratching, clawing, and rubbing of the ears.
Any cat can develop chronic otitis. Ear mites are responsible for approximately 50 percent of ear infections in cats, but prompt diagnosis and treatment of ear mites generally prevents an ear infection from becoming chronic. Environmental allergies (atopy) and food allergies can also cause the problem. Other less common causes of otitis externa include:
The most severely affected patients are often mired in a cycle of inflammation, infection, and thickening of the tissues lining the ear canal, which eventually leads to narrowing of the ear canals, ruptured ear drums, and debris and infection within the middle ear — a highly painful process, to be sure.
Over time, scar tissue occludes the canals, preventing medications from reaching the diseased portions of the canal. The occluded canals also prevent the natural sloughing of the canal’s skin cells, sebum (wax), and hair, which accumulates in both the canal and middle ear, thereby intensifying the infection.
Considering the long-term nature of this condition, chronic otitis is a frustrating disease for both owners and veterinarians. But for the patient, the case is much more critical, given that he typically suffers significant pain. The pain — not to mention the nagging itchiness — associated with these ear infections makes our frustration seem petty in comparison.
Affected cats typically experience recurrent bouts of copious otic discharge, pain, and terrific itchiness. But a significant subset will suffer these symptoms on a constant basis with no respite from their profound discomfort.
The clinical signs of otitis depend on the severity of the inflammation but may include:
As mentioned above, chronic otitis that begins in the outer ear canal can ultimately rupture the eardrum, ending in otitis media and otitis interna. Progression of this infection into the middle and inner ear can be associated with even more severe clinical signs, including development of a head tilt, incoordination, inability to stand or walk, hearing loss, and severe, unrelenting pain.
A medical history and physical examination findings can provide valuable information when trying to diagnose an ear infection. The medical history may include trying to determine how long the ear infection has been going on, whether it has occurred before, and whether any other signs of illness have been observed.
Diagnosis of chronic otitis is usually based on a history of previous ear infections and physical examination findings. Redness, inflammation, discharge, and other changes within the ear will readily indicate the presence of an ear infection. That’s the easy part. The hard part is finding out a) what kinds of microorganisms are taking advantage of the patient’s inflamed ears and b) what’s causing the inflammation in the first place.
Determining both a) and b) generally requires diagnostic testing. In the case of identifying microorganisms, these are the tests most commonly employed:
Microscopy: The most common test used to identify the presence of mites, bacteria, and yeast is a simple evaluation of the discharge obtained from the ear under a microscope. Mites are readily identified in this way. With special staining techniques, yeast and bacteria can also be identified and their characteristics evaluated.
Culture and sensitivity testing: Testing the debris inside a cat’s ear using simple microscopy isn’t always enough when the otitis has been stubborn or severe. Obtaining a sample of the discharge using a sterile swab and submitting it to a diagnostic laboratory will help determine exactly which bacteria and/or yeast are present. This information helps veterinarians devise the ideal drug strategy to treat the infection.
Underlying illnesses leading to the overgrowth of microorganisms will require a different approach. Here are the most common tests:
Otoscopy: An otoscope is a tool used to help a veterinarian visualize the ear canal. This is the ideal tool to help identify the presence of an eardrum rupture, a polyp, or a mass in the ear canal. Unfortunately, most cats require sedation — if not anesthesia — before they’ll submit to this kind of examination.
Allergy testing: Testing for allergies is never embarked upon lightly, but it’s something some owners of cats with otitis externa may be asked to consider.
Food trial: Since otitis externa occurs in some cats with food allergies, food trials can be an important diagnostic tool. A food trial’s goal is to change the proteins the patient eats to those she’s never been exposed to before. If the otitis resolves when the diet is changed, a food allergy may be the underlying cause of the condition. A 12- to 16-week period in which the diet is restricted is considered the ideal approach to undertaking food trials.
All cat breeds are susceptible to otitis externa.
Treatment of chronic otitis is a multistep process. First, the bacterial and fungal (yeast) component must be addressed along with the inflammation. The following strategies are typically employed.
Cleansing the ear canal is always recommended to clear accumulated debris. If the otitis is painful and/or extensive, cleansing should ideally be done with the pet under sedation or anesthesia. Otoscopy is often recommended as an aid in this process.
Topical medication tailored to treat the specific bacteria, yeast, or mites present is typically employed. These are usually available as either ear drops or ointments and include antibiotics, antifungals (to kill yeast), and anti-inflammatory drugs. There are also spot-on flea control products that are effective against ear mites.
Systemic antimicrobials (antibiotics given by mouth or injection) are indicated in some cases, such as if the eardrum is ruptured. Ideally, antibiotic therapy based on the results of culture and sensitivity testing.
Systemic anti-inflammatory medications, such as corticosteroids, are sometimes used to reduce the pain, redness, and swelling. Antihistamines may also be prescribed.
Treatment of the underlying illness is needed to halt this disease. Treatment will depend on the underlying cause but can range anywhere from mass removal and mite killers to diet changes and allergy injections.
Unfortunately, surgical intervention is sometimes required if a tumor or polyp is present or when patients suffer stubborn or advanced versions of the disease.
Because outdoor cats are more likely to be exposed to ear mites, keeping cats indoors can reduce the chances of ear mites and associated otitis externa. Any new kitten or cat being introduced into the home should be examined by a veterinarian to ensure she is ear mite free before being introduced to other cats in the household. Cats at risk for exposure to ear mites should receive regular treatments with a parasite control product that is effective against ear mites.
Regular cleaning and checking of the ears can identify otitis externa early, so it can be treated effectively before chronic problems result.
This article has been reviewed by a Veterinarinan.
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