Ear disease in cats and dogs

Question 1

1. 4 types of factors to consider when approaching a case of otitis externa.

Answer 1

1. Primary
   Secondary.
   Predisposing.
   Perpetuating.

Question 2

Primary factors.
- Most common primary factor of otitis externa.
– others?

Answer 2

Directly induce otitis externa.
- Allergic skin disease (atopic dermatitis most common, CAFR, contact dermatitis).
– ectoparasites –> Otodectes (rarely demodex), FB.
– Uncommonly tumours, hypothyroidism, keratinisation disorders incl. endocrine, autoimmune.

Question 3

Secondary factors.
- examples.

Answer 3

Do not create disease, aggravate it.
Only addressing secondary factors alone may not resolve ear disease.
- Ear microclimate supports complex resident population of microorganisms so easily upset…
- e.g. by inappropriate topical meds.
- e.g. microbial overgrowth.
– Staph. and Malassezia can be isolated from normal ear canals.
- e.g. opportunistic infection e.g. pseudomonas.

Question 4

Predisposing factors.
- examples.

Answer 4

Increase risk of otitis externa.
- ear conformation e.g. cockers and crosses, bulldogs.
- humidity in ear canal.
- inappropriate (over) cleaning – irritant.
- hypertrichosis? – management harder.
- Predisposition to keratinisation disorders.
- Trauma.
- Neoplasia - reduced air flow.

Question 5

Perpetuating factors.
- examples.

Answer 5

Keep disease going.
- Large population of specialised sebaceous glands which produce cerumen:
– sensitive to inflammation and will up-regulate w/ minimal stimulus.
– excessive production and accumulation of cerumen and ear canal discharge.
- Altered components of cerumen encourages microbial overgrowth.
- Excessive cleaning or use of irritant or inappropriate meds will encourage process.
- In chronic proliferative otitis externa.
– excessive granulation tissue.
– scarring, stenosis, deformity.
– calcification of cartilage.
- Glandular tissues undergo inflammatory and hyperplastic changes.
– increases stenosis.
- Persistent ulcerative otitis externa.
- Involvement of the middle ear.

Question 6

Otitis externa clinical signs.

Answer 6

Uni or bilateral.
- head shaking, scratching, rubbing, yelping.
Vertical canal obstruction by moderate to severe hyperplasia.
Ear canal may be firm on palpation due to hyperplasia, fibrosis and calcification.
Discharge - ceruminous, profuse foul-smelling, purulent, yellow-green, dark and tarry.

Question 7

Otitis media/interna clinical signs.

Answer 7

Pain on opening mouth, or eating, or on palpating ears.
Neuro signs:
- facial nerve paralysis, Horner’s syndrome, Hearing loss (adapt to hide this), vestibular e.g. head tilt, deafness, ataxia, strabismus, nystagmus.

Question 8

Investigation of ear disease - what else do we need to know?

Answer 8

• Presence of pruritus / skin lesion elsewhere.
• Previous clinical signs?
• Presence of systemic signs.
• Other animals in household affected?
• Previous or current meds?
• Ectoparasite control programme?

Question 9

Investigating ear disease - PE.

Answer 9

Examine whole body and skin surface.
Check pinnae in detail (scabies, vasculitis).
Determine if there is pain on palpation of the base of the ear due to fibrosis / calcification.
Examine entrance of vertical canal w/ good light.
Check integrity of both ear canals and tympanic membranes.
Otoscopy can be uncomfortable or painful so may need to sedate.
Open mouth as wide as possible - pain in temporo-mandibular joint can be seen w/ otitis media and other diseases.

Question 10

Investigating ear disease - dx tests.

Answer 10

Cytology of ear discharge - tape impressions of skin folds e.g. pinna lesions.
Culture and susceptibility testing of discharge if:
- already treated w/ multiple abx / antiseptic treatments. (topical/systemic).
- risk of antimicrobial resistance.
- rods on cytology (pseudomonas, e. coli, klebsiella, proteus).
Remember normal ears contain Malassezia, Streptococci, Staphylococci.

Question 11

What must be done to allow full assessment of the ears?

Answer 11

Clean ears:
- may require sedation, GA etc.
- if any doubt about TM integrity, use sterile saline to flush.
May need to assess ear canal and reverse stenosis first - oral preds.

Question 12

What is indicated in terms of diagnostics if middle ear disease is suspected?

Answer 12

Radiography / CT scan of tympanic bullae.
Under GA.
May see thickening, lysis, calcification etc.
Otitis media may be present w/o radiographic changes/outward clinical signs.

Question 13

What does a healthy ear canal look like?
What does a healthy TM look like?

Answer 13

Smooth, pink, reasonably hairless, reasonably clean, open canal.
Slightly translucent, greyish, clean, sometime vascular membrane.

Question 14

Investigating ear disease w/ radiography, CT, MRI.

Answer 14

Otitis media not always associated w/ radiographic changes - but if is, can be prognostic indicator.
Thickened or mineralised ear canal.
Stenosis / occlusion of external canal.
Sclerosis of petrous temporal bone.
Thickening, sclerosis of tympanic bullae.
Lysis of tympanic bullae.
Soft tissue opacity w/in bullae.

Question 15

1. What is chronic ear disease typically associated with?
2. Degree of signs in early stages of disease?
3. What to do if increase cerumen due to inflammation of ear canal due to allergic skin disease?

Answer 15

1. Allergic skin diseases and otitis.
2. May be low but with high degree of pruritus.
3. Establish if a secondary infection is actually present with cytology as not to unnecessarily prescribe antimicrobial ear drops. Doing so may exacerbate the problem either by disturbing the microflora or casing a contact reaction.

Question 16

What may be done for ears that are inflamed w/ increased cerumen but not infected?
- potential issue?

Answer 16

Judicious use of cleaner and topical anti-inflammatory preparations may help control head shaking and scratching associated with allergic skin disease.
- overcleaning may disrupt microflora / cause contact reaction.
In some cases, systemic glucocorticoids may be the only means of controlling clinical signs (reduce stenosis etc).
W/ repeated episodes, consider performing an elimination diet trial to investigate CAFR.

Question 17

Endocrinopathies causing of recurring otitis externa?

Answer 17

Hypothyroidism, hyperadrenocorticism, and sex hormone imbalances.
- Older dogs with hypothyroidism may be subtly presenting dermatology signs.
- Look for symmetrical alopecia, changes in hair colour, texture and pigmentation (less regular renewal as not shedding normally), PUPD, behavioural changes.

Question 18

Management of otitis externa at the first visit.

Answer 18

Physical exam.
Otoscopy.
Cytology of ear canal exudate.
C&S testing?
Consider underlying causes - PSPP.

Question 19

Management of otitis at recheck?

Answer 19

Otoscopy - how much improvement?
Cytology - any improvement in numbers of organisms?

Question 20

Management of otitis - further tests.

Answer 20

Imaging procedures - under GA.
Flush under GA?
- middle ear flush?

Question 21

Management of otitis - aims of therapy?

Answer 21

Kill microorganisms in ear canal and middle ear.
Keep ear canal open so topical solutions can reach deeper tissues and air can circulate.
Reduce inflammation and discomfort.
Reduce cerumen production.

Question 22

1. Ear cleaner and topical meds.
2. Steroids.

Answer 22

1. Cleaners help remove debris, cerumen and purulent exudate, and can have antimicrobial and soothing effects.
   After cleaning, apply topical medication.
   - veterinary licensed products usually polypharmacy as combinations of steroid, antibiotic and antifungal agents.
2. Steroids key to opening ear canal and reducing inflammation and discomfort. NSAIDs not helpful for otitis.

Question 23

Management of otitis - antibiotic therapy.
Management if medical therapy unsuccessful or not possible?

Answer 23

Little benefit of systemic antibiotic therapy in otitis externa.
- May have a role in otitis media in cats more than in dogs.
- Neuro signs? – how deep has infection gone?
- Is owner unable to apply topical meds?
– Long-acting products available for SOME otitis externa cases –> Osurnia, Neptra.

May need to consider surgery for chronic / relapsing cases.

Question 24

1. What product is safe if TM ruptured?
2. Product with steroid only?
3. Factors to consider when choosing the best polypharmacy product to use for otitis?

Answer 24

1. Canesten solution - not licensed for vet use but licensed to be safe for middle ears in people. Is an antifungal.
2. Recicort.
3. Potency of steroid - degree of inflammation present.
   Frequency of use - Sore ears prefer less frequent treatment.
   Type of ABX - stewardship.
   Type of antifungal - azole or not.
   Duration of action - some 28 days - need to treat for this long?
   Data sheet for indications and contraindications.
   Patient tolerance, owner ability and compliance - may need systemics – steroids and analgesia.

Question 25

What if the TM cannot be visualised?

Answer 25

Discuss ear flushing to ensure TM can be visualised as intact before prescribing polypharmacy drops. Owners may be happy to take this risk as it is probably low, but never know

Question 26

Tx of pseudomonas otitis.

Answer 26

Can be difficult. Vet licensed products vs off-license products. Consider in TM intact. ABX: - marbofloxacin, orbifloxacin, gentamycin, polymixin B (licensed but inactivated in organic debris - pseudomonas ears full of pus). Antimicrobials: - PCMX (parachlorometaxylenol) - found in some ear cleaners, Tris-EDTA solutions, silver sulfadiazine. Monitor patient carefully for side effects and resistance. Oral and topical glucocorticoids to open canal, reduce discomfort, facilitate topical therapy. - remember infection is a secondary factor. Physical ear cleaning to remove debris and biofilm - use cleaner that can help disrupt biofilm formation e.g. n-acetylcysteine and/or flush under GA.

Question 27

Preventative maintenance of ears.

Answer 27

Primary disease needs managing. Most ears chronically damaged are anatomically abnormal and susceptible to recurrence of otitis. Regular cleaning 1-2 times weekly. - will help owner to notice any recurrences sooner. - may combine w/ topical meds.

Question 28

Clinical signs of Otodectes - ear mites.

Answer 28

Irritation. Profound hypersensitivity reactions in some cats. Others show little to no clinical signs.

Question 29

Otodectes - ear mites Tx.

Answer 29

Selamectin and moxidectin licensed for Otodectes in the cat (and dog). - spot-ons applied on 2 occasions a month apart. Ear meds incl. Canaural for 3w, Surolan for 2w. Isoxazolines (fluralaner, sarolaner, afoxolaner).

Question 30

Polyps in cats... 1. age affected. 2. Clinical signs. 3. Dx. 4. complications?

Answer 30

1. 5m-5y. 2. Persistent aural discharge, otitis, head shaking, scratching, head tilt, nystagmus. 3. Otoscopy, bulla radiography, examine nasopharynx, CT/MRI can be useful. 4. Polyp may regrow after removal.

Question 31

1. Most common ear FBs? 2. Acute signs of FB? 3. Tx?

Answer 31

1. Grass seed. 2. Pain, discomfort, head shaking, scratching. 3. Profound sedation or GA may be required to remove FB safely. Topical antibacterial and anti-inflammatory therapy.

Question 32

1. Aural haematoma pathogenesis? 2. Tx?

Answer 32

1. Poorly understood. 2. Various Sx methods. Glucocorticoids to control inflammation. Evaluate recurring aural haematoma for primary underlying disease.