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.
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.
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.
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