Otitis – an ear infection

Long-term disease of the ear canals is sometimes seen in cats. There are usually bacterial or yeast overgrowing in the external ear canals and sometimes in the middle, or inner ear as well. Permanent damage of the ear canal often happens with long-term disease. Signs include irritation, pain, neurologic signs, and deafness. The infections are always secondary. There is always a primary cause such as parasites, allergy, internal disease, masses or genetic disease. There are usually also perpetuating factors such as swelling of the ear canal.

Your vet will recommend treatment to eliminate the bacteria or yeast with antibiotics or antifungal medication along with investigations and treatment to diagnose and resolve the primary causes and perpetuating factors. These interventions will help to control the signs and to prevent recurrence.

©Sheelagh Lloyd

Ear infections are always secondary to a primary disease of the external ear canals (the tube-shaped part of the ear visible inside the ear). Inflammation of the ear canal causes swelling (making the tube narrow) and an increase in the production of wax. The ears can become very itchy and painful. They can also smell badly. Severe infection leads to rupture of the eardrum and infections of the middle and inner ear, deafness and neurologic signs and difficulty in resolving the whole problem so that the signs recur after treatments.

The disorders or diseases that may be the primary disease include:

• Allergies (environmental and food)
• Ear mites
• Foreign bodies
• Tumors or polyps in the ear

In ears with primary and secondary disease damage occurs that changes the anatomy of the ear canal and stops its normal function. This damage is called a perpetuating factor, it may be reversible with treatment or irreversible; it includes:

• Narrowing of the ear canal from swelling and scarring
• Enlargement and over-activity of the glands so that wax is over-produced
• The ear’s self-cleaning mechanism failing
• Ear drum rupture – meaning that continued topical treatment cannot resolve the deep infections

Local inflammation (redness, discharge) is the first sign of an external ear infection. Your pet may shake its head, scratch its ears, or rub its ears against furniture or the floor. Some pets with severe infections may cry or groan as they rub and scratch their ears. Some pets scratch so severely that their claws create wounds on the skin around their face, neck, and ears. Sometimes the first sign is the owner noticing a bad smell around the pet’s ears.

Occasionally external ear infections may progress to involve the middle and inner ear, leading to more serious signs of disease such as head tilt or deafness.

Your veterinarian will look in the ear for the presence of inflammation, redness, discharge, growths, or other findings. Sometimes, a cotton swab is used to collect debris from the ear. This material can be placed on a slide and examined under a microscope to determine if the secondary infection is due to yeast or bacteria, and to check for mites (a primary cause). Your vet may also collect a sample of ear debris for culture and sensitivity testing, which identifies the exact organisms present and helps your veterinarian select the best antibiotic to treat the infection.

In severe cases, or if the animal is in pain, your pet may need to be sedated. Under sedation, the ears can be gently flushed to remove debris and enable better examination of the ear. This is important to rule out the presence of foreign bodies, to check on how narrow the canal has become and whether the ear drum is intact. X-rays, CT or MRI imaging and other diagnostic tests may be performed to determine if the middle or inner ear are also involved. Other tests will be needed in order to work out the primary cause. This may be straightforward but it can be an involved process.

Once the infection has been identified, most animals with chronic ear infections can be treated at home. Most yeast and bacterial infections can be treated with liquids down the ear canal or oral medication. Steroids are needed to give comfort to your pet and decrease the swelling around the ear canals. Cleaning of wax or pus from the ear canal will nearly always be required.

The primary causes such as foreign body, parasites, or allergy must be treated to prevent problems recurring. Some are curable – ear mites are relatively easy to treat with medication placed directly into the ear or applied topically between the shoulder blades. Allergy often requires lifelong ongoing treatments such as steroids, ear drops or ear cleaners.

If the ear canals have been permanently narrowed or damage is severe, or if there are masses or tumors in the ear canal, surgery may be recommended.