Cats Life at Home

Wired for Sound: Cool Facts About Cat Ear Anatomy

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Reading Time: 5 minutes A cat’s ears are finely tuned instruments. Here’s how they work and the signs of stress that can signal there’s something wrong with them.

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Reading Time: 5 minutes

We all know how our cats’ ears perk up–even if they are seemingly sleeping–when they hear the sound of a treat bag being opened. The 32 muscles found in each ear of the cat get an amazing daily workout. Their position and movement express a broad range of feline moods and emotions. But more than that, ears are the secret behind a cat’s amazing hunting prowess. Here’s how they work.

Cats are known for their hearing acuity. They rely on their hearing to determine location and movement of prey, as well as to avoid being preyed upon. Cats can hear sounds pulsating at 60,000 vibrations per second, while humans can hear only 20,000. Each ear can move independently to detect the direction from which a sound originates and amplify it.

Ear Structure

The cat’s ear is made up of three parts. The outer ear consists of the pinna (the outer ear flap) and the ear canal, a narrow tubular passage that allows sound to enter the ear.

The ear drum marks the beginning of the middle ear; it’s a thin, taut membrane that vibrates in response to sound waves, transferring them to a small, air-filled chamber (the bulla), which holds three tiny bones—the hammer, the anvil, and the stirrup. Their job is to transmit the vibrations to the inner ear.

The inner ear lies deep within the cat’s skull. It contains the cochlea, a snail-shaped structure with nerve endings that receive vibrations and send them to the cat’s brain to enable hearing. The inner ear also houses the vestibular system, which contains nerves and receptors that govern a cat’s sense of balance.

You may notice that your cat will often shake her head after lying down or doing something active. This is to realign the fluid in their ears, which helps them with balance.

When Ears Go Wrong: Deafness

Deafness in cats is most frequently found in white, blue-eyed cats and is caused by the dominant white (W) gene. According to a study of mixed-breed white cats, by George Strain, Ph.D., a leading expert on deafness in cats and dogs, 50 percent were deaf in both ears or in only one ear. The number rose to 96 percent with the offspring of two white parents.

Deaf cat Princess Charlotte. Photo by Mary Johnson

In addition, Dr. Strain noted that longhaired white cats were reported to have a higher prevalence of blue eyes and deafness than shorthaired cats, but it is not certain whether this observation would stand up in a larger study. Purebred cats carrying the W gene (such as Turkish Angora, Persian, Scottish Fold, Cornish Rex, and Oriental Shorthair) are potentially susceptible to deafness.

Deafness may also occur in older cats as the eardrum thickens or as a result of medications, such as certain antibiotics or diuretics.

Other Ear Ailments

Healthy ears are clean, the same pinky-gray color of the cat’s skin, with no odor when sniffed. Clues that an infection is brewing include excessive head shaking or scratching and an unpleasant odor. Your veterinarian will use an otoscope to look inside the ear and view swabs under a microscope to determine the problem. Left untreated, diseases of the ear can cause neurological and balance issues, not to mention pain and discomfort.

Mite infestation (Otodectes cynotis) is the most common ear-related affliction. Mites are likely if it looks as if your cat has a black, tarry substance within the canal. Mites can be seen moving with the naked eye, so it’s no wonder kitty is scratching and shaking her head.

We know they are unpleasant thanks to the experiments of veterinarian Robert Lopez in the 1980s. Whether curious, brave, or foolish, Dr. Lopez infected himself with ear mites from a cat, not once but three times. He reported immediate scratching and moving sounds, and an itching sensation, merging into a “cacophony of sound and pain.”

While ear mites can be persistent, they are easily treated with medication prescribed by your veterinarian, who may also deep-clean the ear. Mites are highly contagious, so if you have multiple pets and one has mites, they all are likely become infected and require treatment.

Bacterial or yeast infections of the outer ear, known as otitis externa, typically occur among cats prone to seborrhea, which is caused by oily secretions and results in a waxy buildup. If untreated, it may move to the middle ear (otitis media) or to the inner ear (otitis interna).

Signs are head shaking and scratching, as well as redness and swelling and a bad odor. Your veterinarian may flush the ear canal and prescribe topical and anti-inflammatory medications. Different medications will be prescribed if the infection progresses to the middle ear. Your cat can also benefit from pain medication as infections and the resulting treatment may be painful.

Mange (demodicosis) is more of an external ailment. It causes intense itching that can lead to self-mutilation and thick, crusty, scaly skin. Diagnosis is determined through a skin scraping examined microscopically by your veterinarian, who can then prescribe an appropriate medication.

Polyps can occur in the cat’s middle ear, where the eustachian tube is located. Signs include the usual head shaking and scratching, along with head tilt, drooping eyelid, constriction of the pupils (Horner’s syndrome), heavy breathing, and nasal discharge. Polyps can occur in one or both ears, often in younger cats. Surgery under general anesthesia is required to remove them, which cures the problem as long as the entire polyp is removed. Surgery can have risks so discuss the pros and cons with your veterinarian before proceeding.    

Cysts can occur in any area along the ear canal, either singly or in clusters. Small cysts are usually not a problem, but if debris accumulates or the ear canal becomes blocked, the eardrum may become perforated. The lesions can be removed surgically or by laser or freezing (cryosurgery), followed by steroid treatment. They may or may not grow back; however, laser treatment seems to be most effective in preventing regrowth. 

Light-colored cats who are exposed to excessive sunlight may develop squamous cell carcinoma, cancer on the ear tips or other extremities. Apply cat-safe sunblock for protection if your kitty has a catio or goes outdoors.

Cats who go outside may get foreign bodies such as grass or briars stuck in their ears. If they can’t be extracted easily with tweezers, a visit to the veterinarian is needed.

Likewise, outside cats who get into fights may be on the receiving end of bites, scratches, or puncture wounds around their ears that may result in hematomas.  Check with your veterinarian if you notice swelling or tenderness on or around the ears.

Allergies can show up as irritation of the cat’s ears and head, resulting in itching and scratching. Talk to your veterinarian about ways to diagnose or rule out allergies.

By keeping an eye on your cat’s perky pointed ears, they will remain healthy and she won’t miss a beat when the treat bag rustles.   

This article was reviewed/edited by board-certified veterinary behaviorist Dr. Kenneth Martin and/or veterinary technician specialist in behavior Debbie Martin, LVT.

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