Diagnosing nasal disease in dogs and cats.
Most of us sneeze once or twice on most days. We know there are certain environmental conditions that can promote benign excessive sneezing and we try to avoid these if possible. Things are similar for our pets who are constantly exploring their world by enthusiastically sniffing everything. It is common for them to inhale dust and debris as they explore and this material is typically expelled by a sneeze or two. The canine and feline nose are uniquely designed to be very sensitive sensory organs and a very effective filters at once.
Clinical signs of nasal disease include excessive sneezing and nasal discharge that could be clear, mucoid, purulent (pus) or bloody. In some cases, nasal discharge is intermittent, perhaps only observed during or after a sneezing episode. In other cases, the discharge occurs continuously even when the pet is not sneezing.
In advanced cases of nasal disease, there may be facial swelling or changes in the position of the eye that indicate an expansile swelling is originating from the nasal cavity. In most cases, these advanced clinical signs represent an aggressive tumor or serious fungal infection of the nasal sinus.
The nasal cavity is a very difficult place to examine. It is almost completely surrounded by bone with very natural points of entry at the nostrils and above the soft palate. This means there is no easy way to investigate nasal disease when it becomes necessary to do this.
^^ This is a normal radiograph of a dog's skull and nose.
Classic nasal disease workups typically begin with empirical medical therapy that may include antibiotics, antihistamines or corticosteroid drugs. These medications may be used singly or in combinations to determine if there is a positive clinical response in the patient. A positive response often tells the veterinarian something about the cause of nasal disease in general, but typically cannot provide a specific diagnosis. Of course in some cases, clinical signs can completely resolve using empirical therapy and everyone is happy.
In other cases, nasal disease responds partially, temporarily, or not at all to empirical therapy. These patients suffer from chronic nasal disease that may be due to chronic severe infections (bacterial and/or fungal), presence of nasal foreign bodies, or nasal cancer.
^^ The dog on the left had nasal discharge and snzeezing, but had normal skull radiographs.
The dog on the right also had nasal discharge and sneezing, but has very abnormal skull radiographs (likely cancer in the nose).
Advanced nasal diagnostics traditionally begin with radiographs to visualize structures of the skull - especially the sino-nasal region. But high quality diagnostic radiographs are often difficult to obtain. The patient must be heavily sedated or anesthetized to obtain this special study. Positioning of the patient must be precise and the radiographs can be confusing to interpret for even the most experienced veterinarians.
At Lakeland Veterinary Imaging, we believe that chronic nasal disease represents a classic indication for CT imaging. We recommend CT be performed in lieu of radiographs as it provides much more diagnostic information than radiographs for only a small increase in cost to the pet owner. The three dimensional imaging obtained in CT examination provides precise localization of any lesions and determines the most likely cause of nasal disease prior to additional diagnostic testing.
^^ This dog had sneezing and nasal discharge for months. The CT scan showed no evidence of cancer, but a biopsy was collected and this patient was diagnosed with inflammation of the nose (rhinitis).
In most cases, CT examination is followed by nasal biopsy. This biopsy procedure can be performed using lesion location data obtained on CT images. In some cases (especially with small focal lesions), the biopsy requires guidance of an endoscope. During this procedure, swab samples are typically obtained to culture for infectious organisms.
If your pet has clinical signs of chronic nasal disease and has responded inadequately to empirical medical therapy, call or email the imaging professionals at Lakeland Veterinary Imaging. We would be happy to advise you whether advanced diagnostic imaging is indicated and can provide an estimate of fees for the procedures we believe are necessary to diagnose the problem. We want to help you get an answer so that appropriate therapy can begin for the patient. In cases requiring complicated treatment or monitoring, we can also help you select an area specialist to provide this treatment.
-- Dan Heder