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Bacteria In Cat EarsUpdated 10 months ago

An overabundance of bacteria can cause clinical signs like ear odor, ear discharge, scratching at ears, or head shaking.

Ear discharge from a bacterial infection can be brown, black, yellow, or white. There are two main forms (shapes) of bacteria commonly detected from an ear swab cytology: cocci (sphere-shaped) and bacilli (rod-shaped). Low numbers of bacteria usually live harmlessly on the surface of healthy ear skin; so, it’s common and quite normal to find small (occasional) numbers under the microscope. This is especially true for cocci, while less so for bacilli. If no bacteria are detected (none seen), that’s normal too. 

Even though we share some types of ear and skin bacteria between pets and people, they aren’t contagious. This is because there’s almost always an underlying reason(s) the bacteria overpopulate to cause clinical signs. If the bacterial counts are high (1+, 2+, 3+, 4+) in your cat’s ear swab samples, and especially if with one or more clinical signs, then a physical exam of your cat’s ears is needed by a veterinarian. While both cocci and bacilli are forms of bacteria, each type is generally susceptible to different classes of antibiotics. 

Treatment of bacterial infections in the ear typically involves prescription antibiotics. These can come as antibacterial ointments topically applied to the surface of the ear or given by mouth, and/or antiseptic wipes and ear flushes that inhibit bacterial growth. Retesting with an ear cytology after treatment and a recheck ear exam, even if symptoms have improved, is commonly done by veterinarians to ensure that the bacterial numbers have returned to normal (none seen or occasional).

Click here to learn more about bacteria and ear infections in cats.

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