1. Ear Anatomy and Cytology
Clinical Pathology

2. Normal anatomy
The ear canal is a cartilaginous structure lined with skin (epithelium).
Hair follicles, sebaceous glands, and apocrine glands line the entire canal to the eardrum.
In the normal ear, glandular secretions and epithelial cell migration, move dirt and debris away from the ear drum.
A normal ear exam should reveal a smooth, non- inflamed epithelial lining and an intact tympanic membrane.

4. Anatomy continued…..
The tympanic membrane is a thin, semi- transparent membrane that separates the external canal from the tympanic cavity.
Transmits sounds to the hearing apparatus.

6. Otitis
Definition: Inflammation of the ear canal and/or pinnae.

7. Otitis externa
Inflammation of the ear canal to the tympanic membrane.

8. Otitis Media
Inflammation of the tympanum and the tympanic bullae.

9. Otitis Interna Inflammation of the hearing apparatus.
Neurologic signs and deafness are usually present.

10. Causes of ear disease Abnormal conformation Ectoparasites
Systemic diseases, allergies, endocrine disease.
Tumors
Foreign bodies
Trauma

12. Diagnosis of ear problems
Clinical signs:
Inflamed ear canal
Color of discharge
Neurological signs
Otoscopic exam
Ear swab cytology
Culture/sensitivity

14. Ear Cytology Technique
Using a cotton tip applicator, gently swab ear canal.
Gently roll the swab along a clean glass slide.
Heat fix
Stain
Diff-quick
Gram stain

15. Cytological exam Bacteria Yeast WBC’s Epithelial cells
Rods or cocci
Pseudomonas, Proteus, Staphlococcus, Streptococcus
Yeast
Malassezia pacydermatitis
WBC’s
neutrophils
Epithelial cells
Neoplastic cells
Earmites

18. Bacterial Otitis
May see large numbers of bacteria, often phagocytized bacteria in neutrophils.
May see large numbers of neutrophils.
May have mixed infections (rods and cocci)
Discharge color
Creamy, dark, yellow-light brown usually is Staph/Strep
Thick, odorous, pale yellow discharge usually is Pseufomonas, Proteus
Do culture/sensitivity especially if rods are found

19. Malassezia Otitis Yeast are normal inhabitants
>10 yeast/HPF is abnormal.
Discharge: dark brownish exudate, yeasty odor.
May be present with bacteria (mixed infection).

21. Treatment of Otitis Depends on organism causing problems. Topicals
Antifungals
antibacterials
Systemic drugs
Antibiotics
Treat underlying disease