Chronic Otitis (Ear Infections)

Otitis externa refers to inflammation and/or infection of the outer ear canal, (ie above the ear drum), in dogs and cats. This commonly occurs as a reaction to an underlying problem. Otitis media is when the middle ear is affected (ruptured ear drum) and otitis interna when the inner ear is affected (often with balance problems) 

Symptoms:

Frequently include head shaking, head held down to one side, scratching at one or both ears, odour from the ears and pain when you touch the area. In chronic cases this may have been going on for months – years. Most cases have been on multiple forms of treatment throughout this time with minimal success or limited period success. 

Anatomy:

The ear canal is an “L” shape and this favours accumulation of wax, dirt and water at the bottom of the canal.  Any moisture or debris will reduce air flow and provide the perfect environment for bacteria, fungus or yeast to overgrow in your pet’s ear.  If inflammation is severe enough the canal can become thickened, further reducing air flow.  Thus a vicious cycle is created. 

(diagram from “Ear Care and Disease” by Holly Nash, @ www.peteducation.com)

Underlying problems

These can include objects in the ear (e.g. grass seeds), parasites such as ear mites or allergies and moist ears from frequent swimming.  Pets which have floppy ears or ears with a lot of hair in them, may also be more prone to ear problems. 

Allergies occur very commonly in dogs, and less commonly in cats.  These usually manifest as itchy skin, with or without ear involvement. Animals can be allergic to particular foods, chemicals they come into contact with, or things in the environment such as grasses, pollens and insects.  These may occur seasonally (e.g.. every summer) or year round. 

Diagnostics                         

Depending on the duration of the problem and likely cause, the approach to diagnostics and treatment may vary greatly. There are generally certain procedures that are often performed prior to treatment as well as during treatment. The importance of ascertaining the underlying cause is paramount in treating chronic ear problems appropriately and preventing severe distortion of the ear canal and permanent hearing problems. 

• Proper visualisation of the ear canal and ear drum - this often needs to be performed under a general anaesthetic
• Cytology of the ear canal – this is essential to ascertain the general type of infection and also gives us a base to work off to assess response to treatment
• Swab with culture and sensitivity of the ear canal – this is performed in most cases to enable us to choose an appropriate antibiotic for your pet’s treatment. Because chronic cases often have resistant type of bacterial infections, it is essential to see which antibiotics are going to work
• Thorough cleaning of the ear canal – also under an anaesthetic
• X-rays of the middle ear
• CT scan of the middle ear in a small number of cases
• General blood tests – these maybe required to evaluate the presence of any underlying disease (e.g. thyroid problems) that may be predisposing the ears to chronic infection
• Allergy work-up – this is often required in cases where an underlying allergy is suspected 

Follow-up visits involving rechecking the cytology of the ear canal as well as visualisation of the canal and ear drum, are absolutely vital in managing chronic cases effectively.

Treatment

Initially, treatment is aimed at treating the infection and finding the cause.  If these are not kept under control then ear problems are likely to recur. 

An anaesthetic is almost always  required to rule out foreign bodies like grass seeds and to thoroughly check and clean the ear as well as do x-rays and check the ear drums. 

Samples need be taken to examine under the microscope or send to the laboratory.  These are required to differentiate between the various yeast and bacteria types which may infect the ear. 

Depending on the extent and various causes, treatment approaches vary greatly and may include:

• Ear ointments/ medications – these are almost always required. Any medication placed down an affected ear canal has the potential to cause what we call ototoxicity (damage to the middle and inner ear). Intactness of the ear drum is often the factor that influences this, however, ear drums can appear intact at the time of examination and rupture a few days later. If your pet displays any balance problems, vomiting and/ or head tilt, whilst on medication – please stop administering anything into the ear and call us immediately.
• Antibiotics
• Pain killers
• Anti-inflammatories – most often in the form of cortisone
• Allergy treatments
• Surgery – often used as a last resort, but in some cases inevitable 

The most common treatment for ear infections, aside from medications to treat underlying problems, is topical ointments or drops to be applied directly into the ear canals.  It is important that these are given regularly as your vet has directed.  You may need another person to help you restrain your pet, so that you can apply the medication as far down the vertical canal as possible.  Do not move the nozzle horizontally, or the sides of the ear canal and/or the ear drum may be damaged.

Length of treatment varies, but in most chronic problems, this is often 3-6 months.

Prevention

The most important part of this is keeping underlying problems, like allergies or wet ears, under control.  If your dog swims regularly, it is important to dry the ear using towel or tissue, while massaging water out of the canal.

Routine ear cleaning with an ear cleaner such as ‘Epi-otic’ can be beneficial to clear debris and keep the ear dry.  Please check with your vet before using this product, as using it in the presence of a ruptured ear drum may cause nerve damage or inner ear damage.

Bear in mind that once your pet has had one ear infection, it may be prone to recurrent problems.  In the most severe cases the canal becomes so thickened that there is no air flow and surgery is recommended to either open the canal or remove it altogether.

Follow Up

It is essential to bring your pet back for a recheck in 7-10 days to check his/her ears. With chronic cases, regular check-ups are required and re-examination of the ear canal/ ear drum and cytology (microscopic examination) in the ear are a very important part of monitoring and adjusting treatment. 

Patience and perseverance are the 2 most important aspects of chronic otitis treatment. These problems have often persisted for months and sometimes even years – they most certainly will not be sorted with 7 days of treatment!

We encourage an open channel of communication with our veterinarians and if you are experiencing any problems with the administration of any medications or with the outline of your pet’s treatment plan, please give us call.