How to treat dogs ear infection

Inflammation of the inner ear is called otitis interna, and it is most often caused by an infection. The infectious agent is most commonly bacterial, although fungus (otherwise known as yeast) can also be implicated in an inner ear infection.

If your dog has ear mites in the external ear canal, this can ultimately cause a problem in the inner ear and pose a greater risk for a bacterial infection. Similarly, inner ear infections may develop if disease exists in one ear canal or when a benign polyp is growing from the middle ear. A foreign object, such as grass seed, may also set the stage for bacterial infection in the inner ear.

Are some dogs more susceptible to inner ear infection?

Dogs with long, heavy ears seem to be predisposed to chronic ear infections that can ultimately lead to otitis interna. Spaniel breeds, such as the Cocker Spaniel, and hound breeds, such as the Bloodhound and Basset Hound, are the most commonly affected breeds. Regardless of breed, any dog with a chronic ear infection that is difficult to control may develop otitis interna if the eardrum (tympanic membrane) is damaged, as a damaged ear drum allows bacteria to migrate down into the inner ear.

"Dogs with long, heavy ears seem to be predisposed to chronic ear infections that ultimately lead to otitis interna."

Excessively vigorous cleaning of an infected external ear canal can sometimes cause otitis interna. Some ear cleansers are irritating to the middle and inner ear and can cause signs of otitis interna if the eardrum is damaged and allows some of the solution to penetrate too deeply.

What are the signs of an inner ear infection?

The signs of otitis interna depend upon the severity and the extent of the infection. Some dogs may show no outward signs at all, but you may notice your dog is reluctant to chew or seems to be in pain when opening his mouth. He may shake his head or paw at the affected ear.

Your dog may develop a head tilt, usually to the side of the infected ear, and he may even lean, fall, or roll toward the infected side. His balance may be completely altered making it difficult to walk properly, and he may even walk in circles toward the side of the infected ear. If both ears are involved, you may see him swing his head from side to side like an elephant swinging its trunk, and he may have a difficult time staying on his feet. Also, dogs with active otitis interna cannot hear on the affected side(s).

Are there other signs I should watch for?

Vomiting and nausea may occur during the acute phase of otitis interna. If the facial nerve, which is located in the area of the inner ear, is damaged by an inner ear infection, your dog may develop some of the following symptoms:

• drooling from the side of the mouth
• difficulty eating and dropping food
• inability to blink
• development of dry eye in the unblinking eye (see handout “Keratoconjunctivitis Sicca (KCS) or Dry Eye in  Dogs”)
• eye discharge
• drooping of the eyelids, lips, and nostrils on the affected side
• signs of Horner’s syndrome (see handout “Horner’s Syndrome in Dogs”) which include uneven pupil size, called anisocoria (the pupil is smaller on the side on the infected ear), prominent third eyelid, and drooping upper eyelid on the affected side

With long-term facial nerve paralysis the face may actually twist toward the side of the ear infection.

Additional signs include redness in the affected ear and discharge with a foul odor. The outer ear canal may become thickened and hard to the touch from chronic inflammation and the lymph node at the base of the chin on the affected side may become enlarged. Your dog may become reluctant to move at all, preferring to sit or lay in one spot and his head may swing from side to side, even at rest. You may also notice short, rapid, side-to-side movements of the eyeballs called nystagmus.

How is otitis interna treated?

Otitis interna is a very serious condition. If your dog is unable to eat or drink normally due to nausea or disorientation, then hospitalization for intravenous fluid therapy is generally warranted. Nausea must be controlled and dehydration avoided. It may also be necessary to sedate or anesthetize your dog in order to adequately see the ear tissues, take samples for bacterial culture, and appropriately clean the ear.

Treatment of the underlying infection is very important, and your veterinarian will prescribe the appropriate medications. Medications will be administered directly in the ear and orally. Antibiotics (such as amoxicillin-clavulanate, enrofloxacin, clindamycin, or cefpodoxime) will be used for a bacterial infection for 6-8 weeks minimum. If the infection is fungal in nature, an anti-fungal medication (most often itraconazole) will be prescribed. Whatever medications are chosen, it is critical that they be given precisely as prescribed.

"If your dog has an altered balance, restrict his activity during treatment to prevent falling injuries."

If your dog has an altered balance, restrict his activity during treatment to prevent falling injuries. These dogs should not have access to stairs as they may take a tumble. You may also need to hand feed your dog temporarily - reaching down into a dish may stimulate nausea.

Dogs with otitis interna occasionally require surgery if they have relapses, they do not respond to medical management, or if they deteriorate in spite of treatment. Surgery is reserved for dogs with fluid build-up in the middle ear, an infection of the bone surrounding the ear (called osteomyelitis), or a mass (benign or malignant tumor) that arises from the middle ear or the eustachian tube (the tube leading from the middle ear to the back of the mouth). Surgery may be performed to drain the middle ear cavity or, in severe cases of middle and inner ear infection, the entire external ear canal may also be removed. For more information on this surgery, see handout “Total Ear Canal Ablation and Bulla Osteotomy (TECA-BO)”. The severity of the nervous system signs associated with otitis interna does not determine the need for surgery.

Are there any potential complications or long-term effects of otitis interna?

A severe inner ear infection can actually spread to the part of the brain that controls your dog’s breathing and heart rate, although this is quite rare.

Two potential long-term complications of inner ear infection include a permanently altered sense of balance and/or persistent signs of Horner’s syndrome. Your dog may also become permanently deaf in the affected ear.

That said, most dogs with otitis interna respond well to medical management. Expect a two- to four-month course of oral antibiotics to prevent a relapse. The altered sense of balance that generally accompanies otitis interna is typically improved within two to six weeks. Small dogs may recover their balance more quickly than large breeds.

Infection of the external ear canal (outer ear infection) is called otitis externa and is one of the most common types of infections seen in dogs. Some breeds, particularly those with large, floppy or hairy ears like Cocker Spaniels, Miniature Poodles, or Old English Sheepdogs, appear to be more prone to ear infections, but ear infections may occur in any breed.

What are the symptoms of an ear infection?

Ear infections are painful. Many dogs will shake their head and scratch their ears trying to relieve the discomfort. The ears often become red and inflamed and develop an offensive odor. A black or yellowish discharge commonly occurs. In chronic cases the ears may appear crusty or thickened and the ear canals often become narrowed (stenotic) due to the chronic inflammation.

Don't these symptoms usually indicate ear mites?

Ear mites can cause several of these symptoms, including a black discharge, scratching, and head shaking. However, ear mite infections are more common in puppies and kittens. Adult dogs may occasionally contract ear mites from puppies or cats that are infected. Ear mites create an environment within the ear canal that often leads to a secondary bacterial or yeast (fungal) infection.

Since these symptoms are similar and usually mean an infection, why can't I just get some ear medication?

There are several kinds of bacteria and at least one type of fungus that commonly cause ear infections. Without knowing the specific kind of infection present, it is not possible to know which medication to use. In some cases, the problem is a foreign body, a polyp, or a tumor. Treatment with medication alone will not resolve these problems. It is important that your dog be examined to ensure that the eardrum is intact. Administration of certain medications can result in loss of hearing if the eardrum is ruptured. This can only be detected by a thorough ear examination by your veterinarian.

How do you know which drug to use?

First, the ear canal is examined with an otoscope, an instrument that provides magnification and light. This examination allows your veterinarian to determine whether the eardrum is intact and if there is any foreign material in the canal. When a dog is in extreme pain and refuses to allow the examination, it may be necessary to sedate or anesthetize the dog for a thorough examination.

The next step is to examine a sample of the material from the ear canal under a microscope to determine the type of organism causing the infection. Microscopic examination is important in helping your veterinarian choose the right medication to treat the inflamed ear canal. Culture and susceptibility tests are often used in severe or chronic ear infections to ensure your pet is receiving the right medication.

How are ear infections treated?

The results of the otoscopic and microscopic examination usually determine the diagnosis and course of treatment. If there is a foreign body, wax plug, or parasite lodged in the ear canal, it will be removed. Some dogs must be sedated for this, or to allow a thorough ear flushing and cleaning. Many dogs will have more than one type of infection present (e.g., a bacterium and a fungus, or two kinds of bacteria). This situation usually requires the use of multiple medications or a broad-spectrum medication.

"Many dogs with chronic or recurrent ear infections have allergies or low thyroid function (hypothyroidism)."

An important part of the evaluation of the patient is the identification of underlying disease. Many dogs with chronic or recurrent ear infections have allergies or low thyroid function (hypothyroidism). If underlying disease is suspected, it must be diagnosed and treated or the pet will continue to experience chronic ear problems.

What is the prognosis?

Nearly all ear infections that are properly diagnosed and treated can be successfully managed. However, if an underlying cause remains unidentified and untreated, the outcome will be less favorable. Several recheck examinations may be needed before the outcome is successful.

How important is it to treat an ear infection?

Dogs with ear infections are uncomfortable. Their ears are a source of constant pain and they frequently scratch them and shake their head. This can cause a condition called an 'aural hematoma,' in which blood vessels in the ear flap break, causing a painful swelling that requires surgical treatment. Deep ear infections can damage or rupture the eardrum, causing an internal ear infection and even permanent hearing loss.

My dog's ear canal is nearly closed. Is that a problem?

Closing of the ear canal is another result of a chronic ear infection. This is known as hyperplasia or stenosis. If the ear canal is swollen, it is difficult or impossible for medications to penetrate into the horizontal canal. Anti-inflammatory medications can sometimes shrink the swollen tissues and open the canal in some dogs. Most cases of hyperplasia will eventually require surgery.

What is the goal of ear canal surgery?

There are several surgical procedures that are used to treat this problem. The most commonly performed surgery is called a lateral ear resection. The goal of the surgery is to remove the vertical part of the ear canal and to eliminate the swollen tissue from the horizontal canal. It is relatively easy to remove the vertical canal, but removal of large amounts of tissue from the horizontal canal is more difficult. In some cases, it is necessary to remove the entire ear canal (total ear canal ablation), which may result in permanent impairment of hearing. See handout "Total Ear Canal Ablation and Bulla Osteotomy (TECA-BO)" for information on this surgery.

Is there anything I need to know about administering medication in the ear?

"It is important to get the medication into the horizontal part of the ear canal."

It is important to get the medication into the horizontal part of the ear canal (see above diagram). Unlike our ear canal, the dog's external ear canal is L-shaped. The vertical canal connects with the outside of the ear and is the upper part of the 'L'. The horizontal canal lies deeper in the canal and terminates at the eardrum. The goal is to administer the medication into the lower part of the 'L' - the horizontal ear canal.

The ear canal may be medicated by following these steps:

1. Gently pull the earflap straight up and slightly toward the back and hold it with one hand.
2. Using the other hand, apply a small amount of medication into the vertical part of the ear canal while continuing to keep the earflap elevated. Hold the ear up long enough for the medication to run down to the turn between the vertical and horizontal canal.
3. Put one finger in front of and at the base of the earflap, and put your thumb behind and at the base.
4. Massage the ear canal between your finger and thumb. A 'squishing' sound tells you that the medication has gone into the horizontal canal.
5. Release the ear and let your dog shake its head. Many medications will contain a wax solvent and you may observe debris dissolved in this solvent leaving the ear as your dog shakes its head.

If a second medication is to be used, apply it in the same manner. Typically, you should wait 5-30 minutes before applying additional medications. Be sure to ask your veterinarian for specific directions regarding any ear medication or cleansing agents.

"Do not use cotton tipped applicators (Q-Tips) to do this, as they tend to push debris back into the vertical ear canal."

When all medications have been applied, clean the outer part of the ear canal and the inside of the earflap with a cotton ball soaked in some of the medication. Do not use cotton tipped applicators (Q-Tips) to do this, as they tend to push debris back into the vertical ear canal.