Dog - Otitis Externa (Ear Infections)

How common are ear infections in dogs?

Infection of the external ear canal (outer ear) by mites, bacteria or yeast, is one of the most common types of infections seen in dogs.

What are the symptoms of an ear infection?

A dog with an ear infection is uncomfortable and the ear canals are sensitive. The dog shakes the head and scratches head and ears frantically trying to remove the wax and irritation. The ears often become red and inflamed and develop an offensive odour. A black or yellowish/brown discharge commonly occurs.

Are these not the signs of canker?

Yes. Canker of the ear is a term that used to be used primarily for ear mite infection. There is usually a brownish discharge, scratching and head shaking. Ear mite infections occur most commonly in puppies and will frequently occur in adult dogs in the household after a puppy or kitten carrying mites has been introduced. Because of the intense hypersensitivity (allergic) reaction of some dogs to the mites, self trauma resulting from the irritation will result in secondary infection with bacteria which often creates more treatment problems than the mites alone. By the time the dog is presented to the veterinary surgeon, the original mites may have disappeared, but a significant ear infection remains.

Since the symptoms are similar no matter whether caused by mites, bacteria or yeast, can I not use over-the-counter ear drops?

There are several effective acaricide (anti mite) preparations available without prescription. However, treatment of potential yeast or bacterial infection often requires antibiotic sensitivity tests on samples from the ear to establish the causative organisms and the particular preparations to which they are sensitive. In some cases ear infection may be caused by a foreign body such as a grass seed or tumour in the ear canal. Treatment with medication alone will not resolve these problems. Also, the dog must be examined to ensure that the eardrum is intact since administration of certain medications can result in loss of hearing or even impairment of balance if the eardrum has been damaged. Therefore a veterinary examination is worthwhile.

What is involved with the veterinary examination?

Firstly we will examine the dog to determine the amount of pain and inflammation (swelling) associated with the problem. Then the ear canal is examined with an otoscope which is an instrument that provides magnification and light to allow a good view of the ear canal. If the ear is very sore due to self trauma it may be necessary to sedate or even anaesthetise the dog to carry out this examination. It is important that we determine whether the ear drum is intact and if there are any foreign bodies, e.g. grass seeds etc in the canal. At the same time we will obtain a sample of the wax and discharge from the ear canal for laboratory examination to establish the presence of mites, bacteria, yeast, etc. and, if necessary, further tests may be carried out to establish appropriate antibiotics to use.

What is the treatment?

During the otoscopic examination the ear canal may be syringed and cleansed and any foreign bodies, e.g. grass seeds, ticks etc removed. Laboratory examination will often reveal more than one type of infection, i.e. several bacteria or a mixed infection of bacteria and a fungus (yeast). Then further laboratory tests will establish the appropriate drugs to use. Sometimes underlying problems have to be investigated such as hypothyroidism (low thyroid function) or certain allergies which are responsible for the ear condition. If such conditions are not treated simultaneously treatment of the otitis alone is unlikely to be successful.

What is the prognosis?

Accurate diagnosis and early treatment is essential. If the underlying cause remains unidentified and untreated, secondary changes within the ear canal can lead to chronic problems which sometimes can only be resolved with extensive surgery. These are not the only problems. Constant head shaking and scratching can result in broken blood vessels in the ear flap, leading to cauliflower ear (aural haematoma), this requires separate surgical intervention. Also chronic ear infections can penetrate the eardrum and result in internal ear infection sometimes affecting balance.

I cannot see into my dog’s ear canal. Is this a problem?

Thickening and closing of the ear canal is usually a result of chronic ear infection. Medications are available that will help to reduce the swollen tissues but many cases require surgery.

What is the aim of this surgery?

Depending on the extent of the thickening and closure of the ear canal surgical techniques are available to remove the lateral (outside) wall and thus provide relief for the dog. This is one of the unfortunate problems that can arise if early treatment of otitis is neglected.

How do I get the medication into the ear without my dog shaking it everywhere?

The dog’s ear canal is L-shaped. Please refer to the diagram. It is important that drops or other medication penetrate the lower or horizontal part of the ear canal.

1. Gently take the pinna (ear flap) and hold is straight up with one hand.
2. Apply a small amount of medication into the vertical part of the ear canal keeping the pinna elevated so that the medication can run down vertically and enter the lower, horizontal part.
3. With your finger and thumb at the base of the ear flap, gently massage the ear canal, helping the medication to penetrate the horizontal canal (and inducing a tell-tale squelching sound).
4. Release the ear so that your dog can shake the head. Excess medication together with any debris and wax will usually be shaken out.
5. Finally clean the outer part of the ear canal and the inside of the ear flap with tissues or cotton wool soaked in some of the medication. Do not attempt to use cotton buds in the ear canal except under instruction.