Diagnostic tests used to determine the cause of nasal discharge will be considered by your veterinarian based on findings from the physical examination, prior tests
results, or lack of response to empiric therapy. Most tests for evaluation of nasal discharge are best accomplished with sedation or general anesthesia
. The evaluation for nasal discharge may include an oral examination, nasal examination, cytology (examination of cells), biopsy, culture, radiography or computerized tomography. Although routine blood screening rarely identifies the cause of nasal discharge, it can identify concurrent disease and help to assess anesthetic risk.
A platelet count and coagulation screen is important in cases of epistaxis (bleeding from the nostrils).
A nasal swab and microscope examination of the cells (cytology) is helpful in suspected cases of certain cancers.
Specialized blood tests for fungus infections may be appropriate.
Radiography – General anesthesia is usually necessary for optimal positioning. Nasal X-rays can be very difficult to interpret and a second opinion by a veterinary radiologist (a specialist) is helpful in some situations.
Rhinoscopy – is a procedure that consists of looking into the nose (front and back) with a lighted instrument or endoscope. This is performed under anesthesia to visualize and biopsy the nasal cavity as needed.
Culture – Secondary infection is common with most causes of nasal disease. A culture will help determine which organisms are present but one should understand that the normal nasal cavity is colonized by bacteria and sometimes by fungus.
Biopsy – Tissue samples should be submitted for histopathology to assist in the diagnosis. Samples may be obtained by exploratory surgery (usually a last resort), by endoscopic direct biopsy (rhinoscopy) or by blind biopsy using an endoscopic pinch biopsy forceps without directly seeing the abnormal tissue).
Depending on the situation, your veterinarian might recommend additional diagnostic tests to exclude or diagnose other conditions and to provide optimal medical care for your pet. Some examples include:
Serology – can be used for diagnosis of fungal-based nasal discharge.
Computed tomography (CT) – available at referral institutions and excellent for determining the amount and extent of bony involvement of a nasal tumor.
Magnetic resonance imaging (MRI) – available at referral institutions and helpful for determining the amount and extent of bony involvement of a nasal mass.
Surgery – Exploratory surgery can expose the nasal cavity, procure a biopsy, culture and remove foreign bodies.