Detecting ear and hearing problems requires careful observation by pet owners. All mammals generally share the same ear anatomy so basic knowledge of the ear's structure and functions can aid pet owners in the care of this remarkably sensitive organ.
The ear is divided into three major sections: the outer, middle and inner ear. The outer ear consists of the visible portion of the ear and the auditory (ear) canal which ends at the eardrum. Depending on the animal's species and breed or breed combination the outer ear comes in a variety of shapes such as long and floppy, pricked, erect and triangular. The outer ear has muscles that allow the ears to move for locating the source for sounds — a survival adaptation. The ear canal is lined with skin, hair and wax glands.
The middle ear is an air-filled chamber in the skull that contains the tiniest bones of a mammal's body: nicknamed the "hammer," "anvil" and "stirrup." This chain of bones is connected by muscles, tendons and ligaments allowing them to vibrate in response to the eardrum's vibrations from sound waves that enter the ear canal. The middle ear also contains the Eustachian tube that is connected to the throat.
The inner ear begins where the stirrup bone connects to the cochlea-the tiny snail-shaped structure that is filled with fluid and thousands of microscopic hair cells which transform the incoming sound wave vibrations into electrical impulses that the auditory nerve relays to the auditory reception region of the brain. The inner ear also contains the organs for balance and equilibrium.
Healthy pets' ears should appear to be clean inside, free of odor, excessive wax, discharge or particles. Signs of outer and middle ear problems that owners may note include: excessive ear scratching, rubbing ears against the ground or floor, crying out in pain. These symptoms might be caused by wax buildup, ear mites (microscopic parasites), yeast infection, water trapped in the ear, attached ticks, burrs, seeds or other debris. Discharge from an ear may be caused by the rupture of the eardrum due to pressure from fluid trapped in the middle ear. Dogs with long covered ears such as spaniels and hounds may be more prone to have problems because their ear canals provide a warm moist environment for bacteria to thrive.
According to the PetMed website, "deafness refers to the lack of (or loss) of an animal's ability to hear-this can be complete or partial loss." The pet's symptoms may include not responding to everyday sounds (like squeaky toys, its name) or not waking to loud noises. There are numerous causes for deafness in pets such as inflammation of the outer ear, tumors, rupture of the eardrum and middle ear inflammation. Nerve deafness may be caused by degenerative deafness in elderly pets that may at first appear to be "selective deafness" but progresses. Other causes include infections and inflammatory diseases, toxins (like arsenic, lead or mercury), medications, tumors and cancer involving nerves used for hearing, inflammatory masses developing in the middle ear and Eustachian tube and trauma from head injury. Deafness may also be congenital (present at birth.. Several breeds of dogs have been identified as being prone to congenital deafness and include Australian shepherds, Boston terriers, Dalmatians, cocker spaniels, toy and miniature poodles, Maltese and Jack Russell terriers. Congenital deafness in cats appears at an early age especially in white cats with blue eyes and in the following breeds: white varieties of Persians, Scottish folds, Cornish and Devon Rex, Turkish Angora, Maine Coon and Manx.
Care and Prevention
•Research your breed of choice regarding the prevalence of congenital deafness.
•Condition your pet at an early age to allow you to touch and gently examine its ears and reward your pet with yummy healthy treats.
•Examine your pet's ears weekly for unusual odors, redness, swelling, injuries or discharges. Report your observations to your vet.
•Do not attempt to clean your pet's ears if debris, excess wax or a discharge is present. The vet may want take samples for analysis to determine a diagnosis and appropriate treatment.
•Report unusual pet behaviors to the vet such as not allowing ears to be touched, failure to respond to familiar sounds and loss of balance.
•Do not use cotton swabs when cleaning a pet's ears because they may push ear wax or debris into the eardrum or injure the delicate skin that lines the ear canal.
•Use vet-recommended ear cleaner by applying it onto cotton balls. Gently insert them into the ears and then massage the ears to loosen wax and debris.
•Protect your dog's ears before bathing or swimming by gently inserting cotton balls into the outer ear cavities.
•Be proactive and teach puppies and young adult dogs to follow basic obedience hand signals for "sit down," "heel," "stay," and especially "come" because those visual commands may be lifesavers when age-related deafness develops.
•Always walk deaf dogs on leash or monitor them within a fenced-in yard.
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Iris Katz serves as a member of the board of directors and as an educational facilitator for the Humane Society of Carroll County. Her column appears on the third Sunday of the month.