Clinical approach to nasal discharge (Proceedings)

Background

Nasal discharge is seen most commonly with diseases of the nasal passages, sinuses and nasopharynx. Occasionally disease involving the lower airways (trachea, bronchi, etc) can result in nasal discharge. Nasal discharge may occur alone or, more commonly, with other signs of nasal or nasopharyngeal disease such as sneezing, reverse sneezing and stertor. The discharge may be unilateral or bilateral. Unilateral discharge is seen more commonly with neoplasia, fungal infections, foreign bodies, and oronasal fistulas that may affect a single nasal passage. Bilateral discharge is seen with more diffuse inflammatory processes, viral or bacterial infections, more extensive fungal disease (damage to nasal septum, sinuses), and more destructive or caudally located tumors.

Characteristics of nasal discharge

There are different types of nasal discharge that have been defined by their appearance and content. Serous discharge is clear and colorless with few cells and when seen alone may be the result of inflammatory or early viral diseases. Mucoid discharge is white or yellow in color, acellular and is seen with chronic inflammation. Purulent nasal discharge is characterized by a yellow to green color, increased numbers of degenerative neutrophils and bacteria. Purulent nasal discharge is seen with bacterial infections. These infections are typically secondary but on rare occasions may be primary. Mucopurulent discharge is a combination of mucoid and purulent discharges seen for reasons described above. Sanguinous discharge implies the presence of red blood cells. The presence of red blood cells implies enough damage to affect vascular integrity. Sanguinous discharge occurs when blood is mixed with another form of discharge and may be seen with neoplasia, fungal infection, foreign body, oronasal fistula, and trauma of the nose and sinuses. Occasionally chronic inflammatory disease may result in sanguineous nasal discharge. Frank hemorrhage is commonly referred to as epistaxis. Epistaxis is most commonly seen with trauma, fungal infections and neoplasia. A hemorrhagic nasal discharge can also be seen with systemic disorders such as coagulopathies, thrombocytopenia, vasculitis, and hypertension.

Signalment

The age, sex and breed of the dog or cat may aid in the development of differentials and diagnostic planning. Congenital problems are seen most commonly in younger animals. Nasal discharge as a result of a cleft palate is typically seen at weaning. Congenital choanal atresia results in stertor, nasal discharge and open mouth breathing in a puppy or kitten. Infectious diseases such as feline herpesvirus, feline calicivirus and canine distemper are more commonly seen in young animals. Nasal neoplasia is seen more commonly in older, dolicephalic or mesocephalic breeds but rarely in brachycephalic breeds. German shepherd dogs have an immune deficiency making them susceptible to nasal aspergillosis. Miniature dachshunds and whippets have an increased incidence of inflammatory rhinitis.

History

Viral diseases are more commonly observed in non-vaccinated animals. Crowding and exposure to non-vaccinated animal populations predispose to viral infections as well. A young dog with recurrent infections of the lower respiratory tract might raise suspicion of ciliary dyskinesia. A dog or cat that previously had a dental extraction and now has a mucopurulent nasal discharge may have an oronasal fistula. An acute onset of sneezing and facial rubbing should raise suspicion of a foreign body.

Physical examination

Examination of the head may reveal facial swelling, asymmetry and exophthalamus as a result of neoplasia, a fungal infection or a tooth root abscess. Concurrent ocular discharge is common with viral infections (bilateral) or a blocked nasolacrimal duct (unilateral). Cryptococcus, ehrlichiosis, lymphoma, FIP, and hypertension may be associated with other ocular abnormalities. With nasal aspergillosis and cryptococcosis ulceration of the nasal plate is sometimes seen. A good oral exam should be performed to evaluate for gingival bleeding, fractured teeth, palate defects and soft palate displacement (suggests a nasopharyngeal mass). Nasal passages can be checked for patency to determine if unilateral or bilateral disease is present. Regional and peripheral lymph nodes should also be evaluated. Thoracic auscultation is performed for evidence of concurrent lower respiratory disease.

Diagnostics

The appropriate diagnostic work up depends on the diseases suspected. More extensive work up is usually reserved for chronic cases or animals with epistaxis. For epistaxis systemic causes should be eliminated prior to evaluating for local diseases. A physical examination, ocular examination, CBC, biochemical profile, buccal mucosal bleeding time, prothrombin time, partial thromboplastin time, systemic blood pressure, and serology for infectious diseases (Ehrlichia canis, Rickettsia rickettsii), where appropriate, should be performed. Regarding nasal diseases, the CBC is often normal but with allergic or parasitic rhinitis an eosinophilia may be noted, with extensive inflammation or infection a neutrophilia may be noted and, as mentioned above, platelets may be abnormal with systemic causes of serosanguinous discharge or epistaxis such as ehrlichiosis, Rocky Mountain Spotted Fever, DIC and immune-mediated thrombocytopenia.

Diagnostic imaging most commonly incorporates radiography and computerized tomography. Radiographs have the advantages of availability and affordability. Radiographs may readily identify boney displacement (trauma), moderate to severe boney destruction (neoplasia, fungal infection), bullae abnormalities, and tooth root disease. Unfortunately radiographs may not detect more subtle boney destruction and can not differentiate soft tissue from fluid nor define extent of disease. Anesthesia is often required for a complete radiographic evaluation of the dental arcade, nasal passages and sinuses. Computerized tomography is better able to detect subtle boney changes, differentiate fluid from soft tissue and determine the extent of disease. This is also the imaging modality preferred for radiation planning with nasal tumors. Computerized tomography may often be done without anesthesia if only imaging the head. Magnetic resonance imaging may also be used and is a preferred diagnostic technique for soft tissues. Many of the orosinonasal diseases involve bone and are readily identified with computerized tomography.

Endoscopic evaluation of the upper respiratory tract is often necessary in the diagnosis of many chronic infectious, neoplastic and inflammatory conditions. The advantages are visualization of the airways and direct sampling of tissues. Both rigid and flexible systems can be used. Flexible systems make evaluation of the caudal nasal passages, nasopharynx and sinuses (when utilizing a rostral approach) easier. Rigid systems can also be used to evaluate the sinuses but require trephination for access. Both rigid and flexible systems can be used to evaluate the nasal passages. Diagnostic imaging should be performed prior to endoscopy because saline flush and biopsy can distort images.

Ultrasound is used more commonly to aid in the diagnosis of disease of the orbit, sinuses and nasal passages. Periorbital disease can often be detected with this modality and diagnostic samples obtained for culture and cytology. If there has been extensive boney destruction it is sometimes possible to localize tumors affecting the nasal passages and sinuses for sampling.

Specific diagnostics pertaining to upper respiratory tract disorders include serology, cytology, culture, molecular diagnostics, and histopathology. Serology to detect antibodies is most commonly used for infectious diseases such as the feline upper respiratory viruses, canine upper respiratory viruses, canine distemper virus and the tick-borne diseases. Serology can also be used for detection of the cryptococcal capsular antigen in the diagnosis and treatment of cryptococcosis.

Cytology and culture of nasal secretions is generally unrewarding because it lacks sensitivity and specificity. The normal bacterial flora of the nasal passages is diverse and secondary bacterial infections are common with many disease processes. An exception is Bordetella bronchiseptica which has been identified as an uncommon primary bacterial infection in the nasal passages of cats. Even Cryptococcal yeasts are occasionally found in the nasal secretions of asymptomatic animals. Cytology for Aspergillus fumigatus in the presence of the appropriate gross lesions is commonly performed to diagnose this disease. Cytology for fluorescent antibody detection and molecular diagnostic techniques is also performed for viral diseases. For these diagnostic tests the oropharynx, nasal passages and conjunctiva may be sampled. Culture is sometimes used for fungal and viral agents.

Cytology has been used to diagnose nasal neoplasia. Many techniques have been described and although direct visualization and sampling are preferred, a diagnostic sample may be obtained through nasal flushing. When employing these techniques, diagnostic imaging is utilized to localize disease. The nasal passages and nasopharynx are occluded with gauze (nasopharynx) and cotton balls (nasal passage). A red rubber catheter can be placed in the area of interests and saline infused and aspirated. These samples as well as the packing material can be evaluated for neoplastic cells. Occasionally tissue can be obtained this way for histopathology.

Definitive diagnosis of many conditions requires histopathology. Histopathology is performed to diagnose inflammatory, viral (less common), fungal, and neoplastic diseases. Immunofluorescence and molecular diagnostics can also be performed on tissues for viruses. Positive bacterial cultures off of tissues are considered more significant than cultures of nasal secretions. Ideally, histologic samples are also obtained through direct visualization and sampling but blind techniques are also described. Again, diagnostic imaging should be performed to localize disease and the nasopharynx occluded with gauze. Samples have been obtained using open ended devices, such as polypropylene catheters or catheter guards, which will give you a core of tissue. More commonly a cup biopsy instrument is used. Care must be taken with these techniques because of damage to tissues in or outside of the nasal cavity. It is recommended to premeasure any rigid device to the level of the medial canthus (approximates the location of the cribriform plate) and avoid passing a rigid instrument beyond this point.

Differentials for nasal discharge

Infectious

     - Feline herpesvirus-1

     - Feline rhinotracheitis virus

     - Feline calicivirus

     - Canine parainfluenza

     - Canine adenovirus-1

     - Canine adenovirus-2

     - Canine herpesvirus

     - Canine distemper virus

     - Chlamydophila felis

     - Bordetella bronchiseptica (cat)

     - Aspergillus spp.

     - Cryptococcus neoformans

     - Cryptococcus gattii

     - Pneumonyssoides caninum

     - Capillaria aerophilia

     - Linguatala serrata

     - Cuterebra spp.

Inflammatory

     - Allergic rhinitis

     - Lymphoplasmacytic rhinitis

     - Hyperplastic rhinitis

     - Nasopharyngeal polyp

     - Nasal polyp

Neoplasia

Malignant

     - Adenocarcinoma

     - Squamous cell carcinoma

     - Undifferentiated carcinoma

     - Lymphosarcoma

     - Chondrosarcoma

     - Osteosarcoma

     - Transitional carcinoma

     - Hemangiosarcoma

     - Mast cell tumor

     - Malignant melanoma

Benign

     - Adenoma

     - Chondroma

     - Osteoma

     - Fibroma

     - Histiocytoma

Congenital & Anatomic Abnormalities

     - Oronasal fistula

     - Cleft palate

     - Megaesophagus

     - Nasopharyngeal stenosis

     - Cricopharyngeal achalasia/dysphagia

     - Ciliary dyskinesia

Treatment

Treatment is best determined by identifying the underlying condition. This is particularly important in cases that don't respond to empiric therapy. In-depth treatment of specific conditions will not be discussed just a basic review of some therapeutics that may be helpful in the clinical management of your cases. There are some non-specific treatments that are used to help clear respiratory secretions such as humidification, saline nasal drops, decongestants, and mucolytics. Unfortunately these treatments do not achieve a cure but may help reduce nasal secretions, improve appetite and quality of life. Decongestants may actually result in increased nasal discharge and congestion when stopped.

Antihistamines may be useful for cases of allergic rhinitis. Even with allergic rhinitis the response can be variable. It might be necessary to try numerous antihistamines in an attempt to identify efficacy. In addition to commonly used antihistamines (diphenhydramine, hydroxyzine, clemastine fumarate, chlorpheniramine), newer antihistamines and leukotriene antagonists (loratadine, montelukast) can be used. Many of the newer antihistamines and leukotriene antagonists have not been studied extensively in dogs and cats for efficacy or safety.

Antibiotic therapy is most useful in cases of feline upper respiratory and canine infectious respiratory disease (infectious tracheobronchitis) to treat secondary (much more common) or primary infections. This means that their use is most appropriate, and most likely to be effective, in dogs and cats with acute respiratory infections. For chronic respiratory disease antibiotics are used to address secondary infections that may periodically exacerbate signs. In these patients it is common for signs to improve but not resolve with therapy. Empiric antibiotics should be selected with the knowledge of bacterial flora of the upper respiratory tract as well as the more common bacterial pathogens. Antibiotics should be based on culture and sensitivity in chronic or recurrent cases.

Immunosuppression is still commonly used with lymphoplasmacytic rhinitis. Glucocorticoids, such as prednisone and prednisolone remain the most routinely used treatment. Topical glucocorticoid drops and sprays can also be used but may not penetrate secretions. Additional immunosuppressants such as azathioprine (dog), chlorambucil and cyclosporine can be used to minimize glucocorticoid side effects.

Non-steroidal anti-inflammatories that inhibit COX-2 expression have been used for years with various nasal carcinomas. These medications may also have some beneficial effects in animals with lymphoplasmacytic rhinitis as well.

Yunnan baiyao historically was used in Vietnam to stop bleeding and was popularized over the 20th century in several wars. Yunnan baiyao is an herbal that is most commonly used for healing and pain relief. The exact mechanism is unknown but total saponins of patax notoginseng are thought to be the most effective homeostatic ingredient. It is available in many different formulations. In dogs the powder formulation (topically) and capsules are used most commonly for internal and external bleeding. Dosing recommendations are ½ of a 250 mg capsule for small dogs, 1 capsule for medium sized and 2 capsules for large dogs once to twice daily. Safety and efficacy studies are lacking. Regarding nasal disease, this herbal is best suited to decrease bleeding associated with nasal tumors.

Topical antifungal treatments with clortrimazole and enilconazole are still the treatment of choice for nasal aspergillosis. Occasionally disease is only in the sinuses or the sinuses do not communicate with the nasal passages. In these instances trephination and infusion into the sinuses may be required. For nasal cryptococcus, surgical debulking can be performed but medical management with oral azoles is still used most commonly. Itraconazole is effective in most cases but fluconazole is recommended if there is ocular or CNS involvement. Amphotericin B with flucytosine has been used in cats with severe CNS signs. Serology can be monitored to determine response to therapy.

References

Brown NL. Sneezing and nasal discharge in Textbook of Veterinary Internal Medicine 7th ed Ettinger SJ, Feldman EC (eds) Elsevier 2010. pp. 1030 – 1040.

Doust R, Sullivan M. Nasal discharge, sneezing, and reverse sneezing in Textbook of Respiratory Diseases in Dogs and Cats King LG (ed) Saunders 2004. pp 17 – 29.

Kleiter M, Malarkey DM, et al. Expression of cyclooxygenase-2 in canine epithelial nasal tumors. Vet Radiol Ultrasound 2004 May-Jun;45(3):255-60.

McCleod RL, Mingo GG, et al. Loratidine and montelukast administered in combination produce decongestion in an experimental model of feline congestion. Am J Rhinol Allergy. 2009 Nov-Dec; 23(6):e17-22.

Venker-van Haagen AJ, Herrtage ME. Diseases of the Nose and Nasal Sinuses in Textbook of Veterinary Internal Medicine 7th ed Ettinger SJ, Feldman EC (eds) Elsevier 2010. pp. 269 - 74.