A wide range of afflictions can cause discomfort; some may even lead to deafness. Here's how to protect your cat. Among a normal, healthy, and properly cared-for cat’s many distinctive attributes is its astoundingly acute sense of hearing. While the human auditory system is capable of detecting sounds ranging in frequency up to about 20,000 vibrations per second, cats typically can sense sounds pulsating at 60,000 vibrations per second or greater. This impressive acoustic sensitivity has been honed over the ages to serve a cat in countless ways—signaling the stealthy approach of a dangerous predator, for example, or detecting the underground movement of a burrowing rodent. Although most cats will go through life without experiencing a serious problem with their ears, owners should know that a variety of conditions—including congenital defects, infections, trauma and age-related changes—can be extremely painful and may compromise an animal’s hearing. Most feline ear disorders are readily treatable and will not result in permanent hearing loss, notes James Flanders, DVM, an associate professor of surgery at Cornell University’s College of Veterinary Medicine. However, some conditions may render a cat partially or totally deaf, especially if they remain unrecognized and untreated. Ear Anatomy The middle ear contains the eardrum, a taut membrane that vibrates according to the incoming sound waves, and the auditory ossicles, small bones that transmit the eardrum vibrations to the inner ear. And the inner ear—located deeper within the skull—contains the cochlea, a snail-shaped structure containing nerve endings that receive the vibrations and passes them along to the brain, thereby enabling a cat’s hearing. The inner ear is also the site of the vestibular system, a complex arrangement of nerves and receptors that govern a cat’s sense of balance. Congenital Conditions Another primarily heritable abnormality, says Dr. Flanders, is atresia—a defect in the development of the ear canal that may result in partial or total obstruction of the channel. “In this condition,” he points out, “a wall develops in the ear canal that makes it difficult or impossible for sound to reach the cochlea. It’s sometimes operable, and if this wall can be removed, hearing can potentially be restored.” Some cats are born deaf, and the disability cannot be corrected. Due to an anomaly in their genetic makeup, white cats with blue eyes are at greatest risk for congenital deafness. Indeed, says Dr. Flanders, “About 80 percent of white cats with two blue eyes will start to show signs of deafness when they are about four days old as the result of cochlear degeneration.” Acquired Disorders Owners should also keep in mind that a cat’s eardrum thickens with age. Thus, hearing difficulties and potential deafness are often found in geriatric cats. Moreover, deafness can occur as a side effect of various medications—certain antibiotics or diuretics, for example. Among all acquired feline ear conditions, Dr. Flanders notes, the most common by far is otitis externa, an infection of the outer ear canal. This disorder results from infestation of the ear canal with infectious agents, usually ear mites. Otitis externa is most prevalent in cats that are especially susceptible to seborrhea, a skin ailment marked by excess oily secretions from the sebaceous glands. This results in the accumulation of surplus ear wax in which invading mites, bacteria, and other organisms can flourish. If otitis externa is not appropriately treated, the infection can migrate to the middle ear, where it is termed otitis media, and to the inner ear (otitis interna). In the most severe cases, the ear drum and inner ear can be irreparably damaged, resulting in deafness and—because of the condition’s impact on the vestibular system—an acute disturbance of balance on the affected side or sides. Reducing the Risk A few simple measures, he points out, will substantially reduce the chances that a cat will experience a serious ear disorder. He advises the following:
If you observe your cat persistently scratching at its ears, do not probe into them to find the cause. Instead, consult your veterinarian as soon as possible. |