Otitis externa – ear infection

As pet owners, many of us have learned to recognise the signs of an ear infection – scratching, head shaking, and whining are usually the first symptoms of the problem. Ear infections are fairly common in dogs, especially those with floppy ears.

Dr Karin Wilson, a knowledgeable vet from Teva Veterinary Clinic in Somerset West, has kindly provided some valuable insights into the diagnosis, symptoms, potential causes, and treatment of this condition.

About the diagnosis

Otitis externa (OE) is inflammation of the outer ear canal and is one of the most common reasons why a dog is brought to a vet. In dogs and cats, the outer ear canal is a tube that has two components: a vertical part and a horizontal part. The opening in the ear that we see when we look at the inside surface of a dog or cat’s ear leads immediately to the vertical part. This vertical part of the canal extends inward and bends to become the horizontal part, which is narrower in most animals. At the end of the horizontal part is the eardrum. On the other side of the eardrum are the middle and inner parts of the ear. The outer ear is lined with skin that contains glands that produce wax and other substances.

Symptoms

In animals with OE, the skin that lines the outer ear often becomes red, itchy, and painful. Pus, waxy material, and other debris can accumulate. OE can be extremely uncomfortable for your pet and you should notice some of the following symptoms:  head shaking, scratching and rubbing of the ears, a foul or yeasty smell, abnormal behaviour, or even irritability. Patients with a lot of wax or chronic ear infection may also show signs of hearing loss. OE should be treated as soon as possible to prevent infection from spreading to the middle ear.

Potential causes

Causes of OE are usually multifactorial and can be divided into primary, secondary, predisposing, and perpetuating factors.

PRIMARY = factors that directly cause inflammation or disease, such as:

  • Parasites (ear mites are the most common cause of OE in cats).
  • Foreign objects (such as plant or grass seeds; clumps of hair).
  • Keratinisation disorders.
  • Allergies – in many dogs with allergies (to food or airborne allergens), the ear can show inflammation or discomfort before any other part of the skin.

SECONDARY = the bacteria and yeast that have proliferated due to the inflammation and “incubation” environment created by the primary cause.

PREDISPOSING = factors that increase the risk of developing OE, such as:

  • Breed: genetic predisposition to allergy (retrievers, Labradors, spaniels, poodles).
  • Breed: anatomical characteristics (long floppy ears, narrow ear canals, excessive hair in ear canals).
  • Lifestyle: excessive swimming or bathing; humid living environment.
  • Obstructive ear disease: growths in the ear canal.

Diagnosis

If your pet has ear problems, it is important that you thoroughly discuss your pet’s medical history and daily routine with your vet. Details of swimming, bathing, diet, other skin allergies, seasonal occurrence, home care, the first onset of irritation, etc. will all help to determine the specific cause of OE in your pet. Your vet will perform an otoscopic exam if your pet will allow it (look down the ear canal) and take a sample from the ear to determine if there is an infection and to what severity. This is important for monitoring of response to treatment. In some pets, the condition has produced so much inflammation that this simple examination is unacceptably painful, and they may need to undergo sedation for a thorough examination of the ear canals. Treatment without complete examination of the ear canals may be tried, but an underlying problem may be ongoing. Further testing is always warranted if the condition is not improving with treatment.

Overall, with OE, the goals of veterinary care are twofold: to control the inflammation and pain as quickly as possible for comfort (short-term solution) and to attempt to identify any underlying causes to prevent the problem from flaring up as much—or at all—in the future (long-term solution).

Living with the diagnosis

Depending on the cause, treatment of OE can be as simple as placing medication in your pet’s ears and performing regular cleanings, or it can involve a long-term commitment to the management of your pet’s primary and predisposing risk factors.

There is tremendous variation from one to the next in terms of the cause of OE, so the level of treatment and the expected outcome and long-term need for care can range from intensive to simple. Allergies are the most common cause of OE in the Helderberg area. In these cases, allergy management and early detection of ear irritation are vital to keeping OE flare-ups from occurring.

Keeping your pet’s ears clean is important because it helps to prevent an environment in the ears that promotes inflammation. Your vet will show you how to properly do this and which ear cleaning products are safe to use on your pet.

Two good YouTube clips to watch can be found below:

How to Clean your Dog’s Ears in Detail

EPI-OTIC® Advanced Ear Cleanser

For some dogs, a simple lifestyle change can help. For example, if swimming causes moisture in the ears that perpetuates OE, reducing or avoiding swimming may help tremendously. In certain cases, changing your pet’s diet to a hypoallergenic or novel protein diet may be all that is needed to control its ear infections.

Treatment

The treatment for OE requires controlling the inflammation and infection and then treating the underlying cause. Ointments are available to control parasites such as mites as well as bacteria, yeast, and fungi. Not every irritated ear has an infection so these ointments will only be prescribed after a veterinary diagnosis of an ear infection has been made under microscope examination of an ear swab. Ear cleaning solutions such as Epi-Otic are used to remove wax and debris from the ear canal before treatment.

If your pet’s eardrum is damaged, or if inflammation is so severe at first that the ear cannot be handled painlessly, your vet will prescribe cortisone to decrease the swelling and pain in the ear. In severe cases, where middle ear infection is suspected, oral antibiotics may also be prescribed.  For animals with narrow ear canals and severe infection or wax/exudate build-up, flushing of the ear canal will be advised under sedation or anaesthesia so that all of the accumulated debris can be cleaned out properly. Without a clean ear canal, your medicated ointment will not be effective.

In severe and chronic cases, where the ear canal has been permanently thickened and ear infections continue to recur, surgery may be a necessary option. This procedure should only be performed by a surgeon who is experienced therein.

Management & prevention

Learning how to manage and prevent future ear infections is probably the most important step in your pet’s veterinary treatment. If your pet has been diagnosed with an ear infection, you will be asked to return for a follow-up evaluation in a week where your vet will ensure that your pet’s infection has cleared up and tailor a management strategy based on your pet’s primary and predisposing risk factors.

The two most important aspects of any management strategy will be regular monitoring of your pet’s ears to detect ear irritation as soon as it begins and regular ear cleaning.

Owning a dog or cat that is prone to ear infections can be frustrating, so be sure to contact your vet if you have questions or concerns in this regard.

Authored by Dr Karin Wilson (not a SAFREA member)

Proofread and Copyedited by Delilah Sao Joao (SAFREA member)

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