Chronic rhinitis can be a very frustrating disease—for owners and for us! The diagnostic approach to these cases although somewhat limited is well defined. When carefully followed, this approach will usually lead us to a specific treatment. The following discussion outlines my approach to the diagnosis and treatment of these chronic cases.
There are a variety of presenting complaints which may be associated with chronic rhinitis, including:
Sneezing: a normal response to stimulation of subepithelial irritant receptors and a very potent reflex may be abolished with chronic disease. Characteristics such as onset, duration, frequency, and use should be determined. Reverse sneezing, also called the “aspiration reflex,” is a normal response to any irritatation of the dorsal nasopharyngeal mucosa.
Nasal discharge: determine type (serous, mucoid, purulent, bloody etc.), amount, whether (when first noticed) unilateral or bilateral, if the character has changed, and if it is worse at any specific time of the day. The discharge may be due to chronic pneumonia (secretions coughed into the nasopharynx, noticed as nasal discharge).
Respiratory sounds: does the animal make any sound while breathing (with exertion or at rest)? Ask if there has been any voice (bark, meow/purr) changes (laryngeal disorders).
Specific respiratory sounds include:
Stertor, a snoring sound, due to an intermittent physical obstruction usually heard on inspiration (e.g., soft palate).
Stridor, an inspiratory wheeze or noise, typically associated with high cervical tracheal/laryngeal lesions.
Snorting, found with obstructions secondary to secretion accumulation.
I test for airway patency through, and estimate airflow from, each nostril separately. At rest, a healthy animal should be able to breathe without distress through one nostril when its mouth is held closed. If there is any change in effort or noise associated with single nostril breathing, I assume there is some degree of obstruction. Look at the type of discharge and ask the owner how this may have changed over time (response to previous treatments etc.). Facial deformity and/or periosteal pain may be indicative of bony or periosteal involvement—often associated with tumor, fungal infections, or occasionally abscessation of a tooth.
Carefully check the teeth, hard and soft palate (visually and by direct finger palpation), tonsils, and the larynx if it can be seen. The ability to evaluate these areas depends on the animal's cooperation. The neurological status of the pharynx can often be based on how the animal resists pharyngeal manipulation (check the “gag” reflex).
Nasal alar fold depigmentation is encountered with chronic rhinitis and secondary infections (bacterial or fungal). Be careful to differentiate between this and some of the immune skin diseases (e.g., discoid lupus). Schirmer tear testing may detect neurogenic KCS that may also be associated with loss of secretions from the lateral nasal gland, and clinically to a unilaterally dry nose (xeromycteria) with excess nasal secretions that obstruct that side (facial nerve damage secondary to middle ear disease may be involved in these cases).
A variety of diagnostic techniques may be used to help diagnose upper airway (nasal) diseases. There are no hematological or biochemical tests which are diagnostic of chronic rhinitis, but they are indicated in excluding co-existing diseases prior to general anesthesia which is required for other diagnostic tests.
Specific tests include:
For epistaxis: look at platelet numbers and function (mucosal bleeding time), PT/PTT or ACT as well as arterial blood pressure (for systemic hypertension); check medication history for aspirin and alpha agonist use.
For feline calici virus (FCV): only available by virus isolation at this time
For feline herpes virus (FVF), Chlamydia and Mycoplasma: PCR tests are available to help diagnose these agents. The test may be performed on either a conjunctival scraping or tissue (conjunctiva or nasal) biopsy; special transport media is required.
Fungal serology: for canine aspergillosis (not very sensitive) and for feline cryptococcosis (Latex agglutination test– good sensitivity).
Cytology of nasal secretions
Usually obtained during rhinoscopy from a nasal flushing or biopsy. On occasion, it may be of value to examine the gross discharge microscopically. Most times, cytology will simply reveal PMNs, but sometimes you get lucky and find a specific cause for the rhinitis (e.g., parasites, neoplasia, fungal infection).
The interpretation of bacterial cultures from the nose may be difficult, primary bacterial rhinitis is rare in dogs and cats. Cultures taken from the anterior nose/nostril are of little value (reportedly a good reflection of where the dog’s nose has been recently!). Results of anterior vs. posterior cultures are quantitatively and qualitatively different. Fungal cultures can be misleading since fungi can be cultured from healthy animals, and therefore, positive results must be interpreted in light of clinical signs and other tests.
Various techniques have been outlined in the literature; may be used to obtain material for cytology and sometimes for histopathology. Techniques include gross flushing of debris from the nose, flushing and aspirating with a catheter, and or the coring, rigid catheter biopsy technique.
An interesting problem in the nose and best done visually (e.g., look for mites) or on cytology (e.g., use a dissecting or low power microscope for eggs). Nasal mites are commonly encountered in Colorado where HW preventative may be used less than in other areas of the country; nasal mites are reported worldwide.
Skull radiography—preferred views
Area of Interest
Open mouth and/or intra-oral
“Frog-eye” or lateral
Lateral oblique and intra-oral dental films (best)
Nasopharynx / larynx
Lateral—mouth closed, head/neck straight
Radiography of the skull
Requires general anesthesia for optimal positioning and the best interpretation. Attempting to do these on an awake animal will rarely allow for an adequate study and is to be discouraged. Chest radiography should be considered to rule out extra-nasal causes of nasal disease (e.g., megaesophagus, pneumonia).
Also requires general anesthesia but should always be done after skull radiography. Both anterior and posterior rhinoscopy is possible, depending on equipment available. Equipment varies from a simple dental mirror or otoscope, to the more expensive rigid and flexible endoscopes. The determination of the amount of visible space (size of the air channels or meatus) is the basic point to master when scoping dog and cat noses. Be sure to have a good fitting, cuffed endotracheal tube in place to prevent fluid aspiration. Biopsies may be taken either through or along side the scope. Gently make imprints for cytology before fixing tissue and look at them in your practice for an early assessment of the problem. Upon completion of the procedure, consider nasal flushing using large volumes of sterile saline solution under high pressure. Potential complications include bleeding and aspiration (blood, fluid, secretions). Bronchoscopy should be performed if pneumonia is being considered as a potential source of the nasal discharge. See the separate article on respiratory endoscopy in these proceedings.
The third step in evaluating nasal diseases; it is very important that all upper teeth be carefully examined, probing each tooth for the presence of any periodontal pockets which may be indicative of abscessation with secondary nasal involvement. Dental caries, although uncommon, may be a source of infection/nasal cavity involvement; probe the crown of the tooth in order to detect soft areas.
Signs of pharyngeal disease usually are associated with airflow interference and/or the presence of a nasal discharge. Open mouth breathing (without difficulty) in the face of bilateral nasal obstruction is typical. Diagnostics used for nasal diseases are employed (the best ones are the lateral radiograph—look at the nasopharyngeal air column and caudal rhinoscopy).
I have found lymphosarcoma in the dorsal nasopharyngeal mucosa of cats, perhaps because of chronic antigenic stimulation similar to the development of intestinal lymphosarcoma in chronic lymphoplasmacytic enteritis cases. In my experience, these are typically slow growing tumors presenting for signs easily confused with any other chronic rhinitis case.
Nasopharyngeal stenosis or webbing
A problem in cats (primarily) of any age; a transverse sheet of scar tissue formed above the soft palate and obstructing the flow of air through the nasopharynx. Typically has a small pinhole size opening for airflow. Webbing is believed to result during the healing process after various injuries to the air passages (infectious, traumatic). Scar tissue has also been observed within the nasal cavities. Diagnosis is best made via direct visualization (rhinoscopy). Treatment is to surgically resect the lesion, usually via splitting the soft palate, removing the web, and closing the palate. Complications include dehiscence of the palate and reformation of the web.
Treatment of nasal and nasopharyngeal diseases is obviously dependent upon the primary cause of the problem. Secondary bacterial nasal infections are common and the associated discharge often will clear with nearly any antibiotic therapy. Antibiotics with good Gram-positive spectrum are good choices. My preferences include ampicillin, amoxicillin, Clavamox, clindamycin, doxycycline. Azithromycin (Zithromax) has been recommended in cases of chronic rhinitis in cats (e.g., viral induced secondary bacterial infections). Doses recommended are 5 mg/kg daily initially and then every 48 hr for chronic cases (there is a long t½ in cats: 35 hours!). Eventually, treatment must be directed at the underlying problem; examples include nasal foreign body, dental related disorders, and neoplasia. Having lived in a larger city for the past few years, I have become convinced that chronic irritation from air pollutants is a cause of excess nasal secretions in some cases. Diagnosis in these cases is difficult and mostly is by exclusion of other causes and response to anti-inflammatory therapy.
Feline viral rhinitis is probably the most common cause of chronic rhinitis in cats. Secondary bacterial infections are common. L-lysine has been shown to compete with arginine and interfere with viral replication in cell culture experiments. Doses that are recommended for use in cats are 250–500 mg q24h PO chronically.
Effective treatments exist for nasal fungal diseases in small animals (aspergillosis in dogs, cryptococcosis in cats) and include topical enilconazole (or clotrimazole) and itraconazole orally. The inflammatory response to chronic nasal infection (bacterial or fungal) is usually sufficient to result in the loss of nasal turbinates (“destructive rhinitis”) and may be associated with some persistent (serous to mucoid) nasal discharge.
Nasal mites may be treated with ivermectin (300 ug/kg PO weekly x 3) or in Collie breeds using Milbimycin (1 mg/kg PO weekly x 3). This has been such a common problem for me in Colorado that when evaluating sneezing and reverse sneezing in the dog, I routinely recommend treating dogs for nasal mites prior to proceeding with a full rhinoscopy. Other common presenting signs associated with nasal mites include sneezing, serous nasal discharge (not purulent), facial irritation, and epistaxis.
Some nasal conditions result in structural abnormalities (nasal polyps, nasopharyngeal webbing) that cause nasal airflow obstruction but no obstruction to airflow through the mouth. These conditions must be treated surgically (or perhaps endoscopically or with a laser), but prevention of recurrence is important and may be difficult in these cases.
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