Veterinary care should include diagnostic tests and subsequent treatment recommendations. Tests are needed to confirm the diagnosis of otitis externa and exclude other diseases that may cause similar symptoms. The following diagnostic tests are often recommended: Complete medical history and physical examination to examine your pet's external ears. Your veterinarian will pay close attention to the size of the ear canal, presence of pain, smell of ears, presence of hair or foreign material, masses or polyps, character of discharge/exudates, soundness of the ear drum, and general health. Your pet may need to be sedated.
Cytology is used to identify parasites, yeast organisms, bacteria and cellular components. This test will help to determine the cause of otitis externa and choose the proper treatment for your pet. Cytology involves taking a swab of the ear discharge. The character of the discharge can sometimes be associated as follows: Dark black discharge can be associated with ear mites; brown or grey discharge can be associated with yeast infections; and white-yellow-green colored discharge can be associated with bacterial infections.
Culture and sensitivity tests is used in cases of recurrent infections, as there are some organisms that are often resistant to many antibiotics.
Biopsy of growths to determine the presence of tumors.
Radiography (X-rays) to evaluate the degree of the disease.
Your veterinarian may suggest a referral to a dermatologist in difficult or recurrent cases or additional diagnostic tests to exclude or diagnose other conditions or to better understand the impact of otitis externa on your pet. These tests are selected on a case-by-case basis and may include:
A complete blood count (CBC) to evaluate your pet for other problems such as infections or inflammations.
Serum biochemistry tests if there are other abnormal symptoms on the physical examination such as weight loss.
Urinalysis to evaluate the kidneys and bladder.
Thyroid level tests to determine the presence of hypothyroidism, which is the most common endocrine disorder that causes otitis externa in dogs.
Adrenal function tests to rule out Cushing's disease, which is hyperadrenocorticism secondary to excessive pituitary excretion of adrenocorticotropic hormone.
Allergy tests to rule out allergic disease.
Dietary trial to rule out allergic disease.
Fungal cultures in the presence of severe or recurrent fungal infections.
Skin scrapings to rule out mites such as Demodex.