Bacterial otitis externa is less common in cats than in dogs. Ear symptoms are not always bacterial either, so diagnosis requires examination and assessment of a sample.
When to see a vet urgently
Contact a vet promptly if ear symptoms are accompanied by any of the following:
- Unsteadiness, falling or inability to walk normally.
- Involuntary eye movements or a sudden marked head tilt.
- Inability to blink or a different appearance on one side of the face.
- Severe ear pain, refusal to eat or reduced consciousness.
Milder pain, smell and discharge are also reasons to book an examination. You can find a vet near you.
Overview
Otitis is an umbrella term for ear inflammation. The most common feline form is otitis externa, confined to the ear canal. Middle and inner ear infections are less common but much more serious. Bacterial infection often develops secondarily, for example after injury, allergy, parasites such as ear mites, or reduced immunity.
The external canal skin and middle ear behind the eardrum are different areas. The eardrum separates them, while the auditory tube connects the middle ear to the throat. Feline middle ear disease can relate to respiratory disease or an inflammatory polyp and need not begin in the external ear. A polyp is a tissue growth that can disrupt ventilation and drainage.
An inflamed canal swells and fills with discharge. This can prevent medicine reaching the whole treatment area. Long-standing inflammation can alter canal structure, so simply trying another antibiotic does not resolve the problem.
Causes
Key factors in bacterial otitis development include:
- Bacteria, including Staphylococcus, Streptococcus and Pseudomonas.
- Consequences of ear mite infestation, or otodectic mange.
- Allergies predisposing to inflammation and infection.
- Canal injuries or foreign objects.
- High moisture and inadequate hygiene.
- Reduced immunity from chronic diseases.
Ear bacteria do not always mean an infection acquired externally. Some belong to the healthy microbiota and can overgrow when conditions change. Yeast may also be present in the same ear. Alongside treating bacteria, the initial trigger and sustaining factors therefore need investigation.
Poor hygiene does not explain every case. Excessive cleaning and irritants can also damage the canal. Persistent or rapidly recurring symptoms in one ear may instead suggest a foreign object, polyp or another obstructing lesion.
Risk factors
- Kittens and older cats with reduced immunity.
- Animals with chronic allergies.
- Outdoor cats in contact with other animals.
- Cats with abundant ear hair and reduced ventilation.
These factors are assessed individually. Precise evidence on the size of bacterial otitis risk from ear hair or across all young and old cats, for example, is limited. Outdoor access and animal contact may increase ear mite exposure but do not establish bacterial infection alone. An indoor cat's symptomatic ear also needs examination.
Symptoms
Typical symptoms of bacterial otitis include:
- Ear itching, constant scratching and head rubbing against objects.
- An unpleasant ear smell.
- Purulent, dark or yellowish discharge.
- Canal redness and swelling.
- Pain when the ear is touched.
- Head tilting towards the affected ear.
- Balance and coordination problems as infection spreads deeper.
- Reduced hearing.
Discharge colour or smell alone does not identify a bacterium or distinguish bacterial disease from mites. Brown wax also occurs in healthy ears. A new change, pain, itching and inflammatory findings together particularly suggest disease.
Your cat may avoid head stroking or chewing if deeper inflammation makes opening the mouth painful. A head tilt and balance loss need distinguishing from simple ear tenderness: balance signs may involve the inner ear or another neurological disease. Looking into the ear at home cannot establish their cause.
Possible complications
Untreated bacterial otitis can lead to:
- Chronic, recurrent otitis.
- Eardrum damage.
- Spread to the middle and inner ear.
- Neurological signs, including balance problems and head tilt.
- Partial or complete hearing loss.
Severe scratching and shaking can also cause an ear flap haematoma. The flap becomes soft and swollen or thickened and needs separate assessment. Clearing the canal does not necessarily reverse established hearing or nerve damage. Conversely, not every ear infection progresses deeper when identified and treated promptly.
Diagnosis at the vet
Diagnosis is based on:
- Otoscopy to examine the canal.
- Sampling and bacterial culture.
- Cytological examination of discharge.
- X-rays or CT if complications are suspected.
Report symptom duration, previous medicines, cleaning and any skin or respiratory signs. Both ears are examined even if you noticed only one affected side. Pain, swelling or abundant discharge may require sedation or general anaesthesia. The ear need not be forcibly examined while your cat is awake.
Cytology examines a preparation of discharge microscopically. Yeasts and inflammatory cells are assessed alongside bacteria. A small bacterial population without other findings does not confirm infection alone. Culture and susceptibility testing particularly help select medicines for severe, chronic or unresponsive infection. Sampling location also affects interpretation when middle ear disease is suspected.
A normal-looking or intact eardrum does not completely rule out otitis media. CT or MRI can provide more detail on deeper structures than ordinary X-rays. Investigations are selected according to symptoms and findings. A visible tissue lesion may be sampled to identify its nature.
Suspected allergy is investigated separately; food allergy assessment relies on a planned diet trial and challenge, not random food changes.
Treatment
Treatment targets confirmed infection, pain and the underlying cause. The bacterial name alone does not determine medicines: location, eardrum condition and previous response also matter. A topical antibiotic-containing ear medicine may be enough for bacterial otitis externa. Severe or deep infection may require oral or injectable medicine.
If the sample also confirms yeast infection, treatment needs an effective antifungal. Antibiotics alone do not treat yeast or remove mites or foreign objects. Some ear medicines contain several active ingredients, so do not combine products yourself. Selection is based on findings.
Your vet safely removes discharge obstructing treatment and prescribes anti-inflammatory and pain-relieving medicines where needed. Not every ear product can be used with a damaged eardrum, because some can harm hearing or the balance organ. Do not therefore start old drops or another animal's medicine yourself.
A polyp or severely altered canal sustaining inflammation may need surgery. A polyp differs from a malignant tumour, but tissue type is confirmed by examining removed tissue where needed. Middle ear flushing is a veterinary procedure that may involve sampling and anaesthesia. Do not flush a suspected deep infection at home.
Home care and monitoring
Ask for a demonstration of medicine administration and any cleaning before leaving. Use only the agreed product. Vinegar, hydrogen peroxide and other irritating home remedies can worsen inflammation. Do not insert cotton buds or other instruments into the canal. Contact the practice if handling hurts or giving medicines is difficult.
Monitor smell, discharge, shaking, tenderness and general health. Increasing pain or new balance problems after starting treatment require prompt contact. Also report irritation after every application. In addition to visible improvement, follow-up may need repeat microscopy. Do not shorten treatment yourself when symptoms ease.
Prognosis
Many external ear infections resolve once the cause is found and treatment can be carried out. Recurrence may mean an untreated underlying cause or deeper infection remains. Severe middle or inner ear disease may leave hearing or neurological signs even after bacteria are eliminated.
Prevention
- Regular ear checks and cleaning.
- Early treatment of parasites.
- Allergy management.
- Preventing moisture and foreign objects entering the ears.
- Regular veterinary examinations.
Healthy ears do not usually need regular cleaning. Observation differs from vet-selected cleaning of a symptomatic ear. Confirmed ear mites may require coordinated treatment of household cats and dogs.
This text provides general information and does not replace veterinary care. Contact a vet if your cat develops symptoms.
Frequently asked questions
Can a bacterial ear infection spread to another cat?
Inflammation does not automatically mean a transmissible infection, because normal microbiota bacteria can overgrow secondarily. However, underlying ear mites can spread, requiring coordinated treatment of contact animals.
Does a cat always need antibiotic tablets?
No. Topical medicine may be enough for an external bacterial infection. Tablets or injections depend on depth, severity and findings.
Why does inflammation return after treatment?
An untreated polyp, allergy, mites or middle ear infection may be responsible. Recurrent symptoms need examination so the sustaining factor can be treated alongside medicines.
Can middle ear infection occur without discharge?
Yes. The middle ear can be affected without obvious external inflammation, and the eardrum may look intact. Balance changes, pain or abnormal facial movement are therefore investigated even when the ear opening looks clean.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
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