Infection of the ear canal (otitis external) with bacteria and/or yeast is extremely common in dogs, but also occurs in cats. The infections are always caused by a trigger which must be resolved along with the infection itself, or the infection will surely return as soon as treatment has ceased. The most common trigger we see here in East Tennessee is allergy, but persistent moisture in the ear canal secondary to swimming or infection with parasites are other common underlying problems. Fungal infections of the ear canal are also often seen in our practice. The most common cause is an overgrowth of Malassezia yeast, which is part of the normal flora of an animal’s skin but will cause major inflammation and irritation when the population increases abnormally. Just as with bacterial infections of the ear canals, the underlying cause of the yeast infection must be identified and addressed.
Whether the infection is caused by a bacteria and/or yeast, the symptomsof otitis external will be generally the same and include itching, reddening of the ear canal, unpleasant odor, discharge from the ear, and sometimes swelling and bleeding secondary to self trauma as the pet scratches wildly to relieve the intense itch.
Treatment is most often effected through topical drops or ointment applied to the ear canals twice daily by the owner. In cases where this is not possible either because of personal schedules or because of particular dogs’ resistance to treatment, we can pack the ear canals with an appropriately medicated lanolin based product that will last for a full two weeks. If the infection is severe enough, we will sometimes also prescribe oral pain medication for at least the first few days of treatment. We will always discuss the possible trigger for your pet’s ear infection and try to address that problem so the infection will not recur.
Ear mites cause the most serious problems in young cats, but cats and dogs of any age can be affected by these annoying pests. Luckily for us, they will not infect humans. Although it can’t hop or fly, an ear mite (known scientifically as Otodectes cynoti) can crawl. If a bunch of these miniscule parasites should enter your kitten’s ear, make themselves at home and start to breed, they can cause major damage unless promptly evicted.
Typically, symptoms of ear mite infection are obvious. The cat’s outer ear is likely to be inflamed, and she might hold her ears flat against her head, scratch at them almost without letup, and shake her head frequently, as if trying to dislodge a bothersome object. They are also detectable by the mess they make inside an infested animal’s ear canal—a dark crusty or gooey, sometimes foul-smelling accumulation of wax and mite debris in which the tiny critter thrives.
Ear mites are almost microscopically tiny, but it is actually possible to see their rapidly moving little bodies with the naked eye. Ear mites are extremely contagious, moving from one cat to another on close contact and eventually making their way to the ear. Infestation is most common among outdoor cats, whether they’re brawling or cuddling up affectionately.
If ear mite infestation is suspected, it’s important to seek veterinary help right away. Aside from relieving the pet’s miserable discomfort, early treatment can curb infection stemming from the mutilation of the ears and face that can result from aggressive and nonstop scratching. If treated soon enough, we can also prevent secondary otitis externa—an infection of the outer ear that, if untreated, can progress to the middle and inner ear and damage the ear drum. If that happens, it can permanently affect the animal’s hearing and sense of balance.
Ear mites are not difficult to diagnose. We will usually use a cotton swab to gently collect a sample of ear debris for microscopic examination, and the living crawling tiny insects are readily seen.
Treatment generally begins with a thorough cleaning of the cat’s ears to remove any wax or debris that may shield the mites from topical medications. This cleaning is the most difficult part of the treatment, as it seems that “waking up” the ear mites causes intense itching. Once the cleaning is complete, there are a variety of effective treatments available, and we choose which is most appropriate, depending on the particular patient’s condition and attitude.
Aural hematomas are a problem we see in both dogs and cats, but more frequently in dogs. While structurally much simpler than the other components of your pet’s hearing apparatus, the pinna—the fleshy, visible portion of the outer ear—is an essential part of the auditory system. Although dogs’ ears are as varied as dog breeds themselves, they are all subject to this unpleasant condition. The cat’s pinna is a thin, funnel-shaped, mobile structure, supported internally by cartilage and tiny muscles that give the ear its shape. The pinna serves to collect sound waves from the external environment, concentrate them, and channel them into the depths of the auditory canal—the middle and inner ears. Although normally a sturdy structure, protected on both the front and back surfaces by a layer of tough skin, the pinna—directly exposed as it is to the outside world—is subject to various traumas that can lead to a swelling called aural hematoma.
The swelling can be caused by, for example, blunt trauma to the skull or by deep wounds to the ears that a pet may sustain in fights with other animals. The most frequent cause, however, is the self-inflicted trauma of persistent and furious scratching to relieve the relentless itching stemming from otitis externa, an infection of the external ear canal. Otitis externa may result from a yeast or bacterial infection or the invasion of parasites within the ear canal. If the dog or cat scratches and shakes his head adequately, he can rupture blood vessels inside the pinna, and since the blood has nowhere to go, it accumulates and the pinna begins to look like a little pillow on the side of the head. This swelling itself is uncomfortable for the pet, so the self-trauma becomes even more severe.
If an aural hematoma goes untreated, the condition becomes increasingly uncomfortable, and although the condition sometimes can spontaneously resolve, that can take many weeks and by the time the ear heals, it will be deformed. The cartilage takes on an odd, bumpy shape, and the pet ends up with a permanent “cauliflower ear.”
For many decades it was believed that the only effective way to treat an aural hematoma was with an extensive surgical drainage procedure, but recently it has been shown that most of these respond very nicely to medical treatment with a gradually tapering dose of corticosteroids. At Fountain City Animal Hospital, most of our aural hematoma patients do not undergo surgery.
Vestibular Syndrome is a still mysterious syndrome that can affect both dogs and cats, but most commonly we see it in our elderly geriatric canine patients when it is known as, “Old dog vestibular disease.” Although generally not a serious issue, its sudden onset can be very alarming to both patient and owner. A generally healthy dog (or cat, on occasion) suddenly seems to be having trouble getting up on all four legs and maintaining her balance. The animal eventually manages to stand, but her appearance is startling. - as though she were drunk and very confused. Although her vision seems to be all right, her head is oddly tilted to one side, and her eyes dart back and forth wildly. And after taking a few steps, she abruptly lists to one side and tips over again. This disorder and its alarming manifestations are typically temporary and ultimately harmless, but in some cases these signs may be due to a more serious problem so immediate veterinary consultation is certainly in order.
There are two connecting parts of the body that help our pets maintain their balance, and when there is a problem with either one of these, the symptoms of vestibular syndrome arise. One is the vestibular apparatus, located deep within the inner ear, and the other is centered in the lower area of the brain known as the medulla, situated at the top of the spinal cord. The vestibular apparatus consists of several fluid-filled canals that contain specialized nerve cells and receptors.
These receptors, which are connected to nerves leading to the medulla, respond to changes in movement of the fluid that is in the chambers. The fluid shifts as the animal’s head changes position, and corresponding signals are instantaneously sent to the brain; these signals register the position of the head relative to gravity. The vestibular apparatus tells the animal whether its head is motionless or moving and, if the head is moving, which way it is moving. A pet’s sense of balance is normally maintained because the system also compensates for changes in position. If the animal turns one way or another, a signal is automatically sent to the muscles on one side of its body to adjust for the change in position, thus preventing the pet from tipping over.
The most common clinical signs of vestibular disease include circling or falling to one side, a pronounced head tilt, and nystagmus—the rapid and involuntary oscillating movement of the eyeballs.
In the overwhelming majority of cases, the cause of vestibular malfunction remain unknown and are therefore referred to as, “Idiopathic [cause unknown] vestibular syndrome.” Nonetheless, there are a handful of known causes for vestibular syndrome, and they include bacterial infections, inflammatory disease, adverse reactions to certain drugs, and a variety of growths such as polyps, tumors, cysts, and even cancer.
Diagnosis of vestibular dysfunction requires a thorough medical history and physical examination of the patient, including a neurologic exam and an otoscopic exam that explores the pet’s ears for signs of infection, inflammation, or tumors. If we have suspicion of a more serious issue, we will recommend advanced imaging (CT or MRI) at one of our local specialty centers to test for problems deeper within the ear or skull.
Treatment of vestibular disease depends on the cause, but in most idiopathic cases, the symptoms are transitory, arising abruptly and then gradually improving over the course of several days to a few weeks. There is no specific treatment for the idiopathic form, so pets are supported as needed while Mother Nature takes care of the true healing. They must be kept confined in a safe place where they will not injure themselves, and we often administer anti-nausea medication since these patients experience true “motion sickness.” Supportive care may occasionally include assisted feeding and fluid administration if the pet refuses to eat and drink. In most cases, the signs of idiopathic vestibular syndrome will vanish within a short time and will never reappear. If the condition is secondary to infection, tumor, or toxicity, the primary disease must be treated.