OTITIS EXTERNA CAUSE AND DIAGNOSIS
Inflammation of external ear (Otitis externa) may have multiple etiological factors. Otitis externa should be observed as a symptom of an underlying problem that needs to be identified and treated. There are some predisposing factors that make an individual more prone to Otitis externa. Few predisposing factors are:
- Excessive moisture in ear /Moist environmental conditions: Moist conditions like water seepage into ears during bathing, swimming or rainy days may create good conditions for pathogens to proliferate and cause infection.
- Excessive hair /Narrow ear canal: This caused difficulty in cleaning of wax and foreign bodies like grass and pollen from the external ear canal. These foreign bodies may irritate ear causing inflammation.
Causes/Etiological factors of Otitis externa:
- Infectious cause:
- Bacterial infections: Pseudomonas aeruginosa, staphylococcus intermedius, Proteus spp. are few bacterial infections of the external and middle ear.
- Parasitic infections: Otodectes cyanotic (ear mites), demodicosis, sarcoptic mange, otobius Magnini (tick).
- Fungal infections: Dermatophytosis, sporothrix and Cryptococcus spp.
- Yeast infections: Malassezia pachydermatis.
- Hormonal changes: Hypothyroidism, hyperadrenocorticism.
- Hypersensitivity: Atopy, food allergy, drug reactions.
- Tumors or Other growths: Neoplasms, polyps, sebaceous adenitis.
- Dermatological factors: Keratinization disorders.
Diagnosis of otitis should include not only the condition but also underlying factors which are responsible for it. Diagnosis should include.
- Direct and otoscopic observation: Direct physical examination to observe the pattern lesions in the ear and other parts of the body is essential in diagnosis. Ear mites may be present and cause irritation in neck, rump, and base of the tail. Food allergy reactions may be present in another part of the body along with ear. Mange may be present on tip of ear along with canal. Otoscopic examination is done to observe severity of infection and tympanic membrane. In most otitis externa case tympanic membrane are intact. This help veterinarian to suggest a suitable treatment plan for that individual.
- Examination of ear discharge: Ear discharge examination gives good insight into the cause of otitis in dogs. Ear discharge examination includes: Direct microscopy: Direct microscopy is done to diagnose ear mites infestation. B) Slide staining: Making slide and staining can identify bacteria, yeast or fungi responsible for condition C)Culture and antibiotic sensitivity test: This is done to culture and identification of bacteria or fungal species and to identify effective antimicrobial therapy.
- Blood and hormonal tests: Simple Complete blood count (CBC) can tell much about diseases in dogs. High eosinophils suggest allergic reactions. TSH and T4 values are important for identifying hypothyroidism. ACTH test is done to identify hyperadrenocorticism as the cause of ear infection.