Assessing nasal air flow
In cats presenting with nasal discharge, it is important to assess nasal airflow to determine the patency of both nasal cavities
and the nasopharynx. With idiopathic rhinosinusitis, physical examination findings are usually normal with the exception of
the upper respiratory tract. The junction of the hard and soft palate is palpated to detect mass lesions, and the dental arcade
is inspected for gingivitis, tooth root abscessation or oronasal fistula. Regional lymph nodes should be carefully assessed,
and a fundic examination may be helpful if cryptococcosis is suspected.
In most cats with chronic nasal discharge, a diagnostic work-up is performed relatively late in the course of disease and
attempts to control signs for a prolonged period of time have occurred. At some stage, it is important to recommend diagnostic
testing to rule out treatable conditions and to establish the characteristics of the disease.
The diagnostic work-up includes general laboratory work and feline serology (FeLV/FIV testing) to assess systemic health,
followed by general anesthesia for skull radiographs or computed tomography (CT), rhinoscopy with biopsy and dental examination.
Foreign bodies or bony malformations are usually obvious on radiographs or CT, and involvement of frontal sinuses can be readily
detected. Subtle changes in turbinate structures and distinction of soft tissue densities in the nasal cavity are more difficult
When using skull radiographs, the intra-oral radiographic view is most helpful because it provides visualization of both nasal
cavities in sufficient detail. This view is best-achieved using dental radiographic film that is placed inside the mouth during
the exposure. It can also be obtained by placing the corner of a small radiographic plate into the mouth for the exposure,
or by placing the cat in dorsal recumbency, opening the mouth wide, and angling the radiographic beam into the maxillary region.
A frontal sinus radiographic view is difficult to obtain in a cat because the sinuses are so small, and disease in this region
can be missed on radiographs. In the cat with rhinitis, imaging generally shows variable degrees of turbinate lysis and increased
fluid density within the nasal cavity.
Sinuses are often involved in the disease process as are tympanic bullae. Disease is usually bilateral but some cases are
remarkably unilateral. Overall, CT provides better evaluation of the entire upper respiratory tract than do radiography, and
it can detect cribriform invasion, which is an important determinant of prognosis in animals with nasal neoplasia or fungal
infection. Both radiographic and CT changes in cats with rhinitis can mimic those found with neoplasia indicating the need
to proceed with visualization of the nasal cavity and biopsy.
The rostral nasal cavity and caudal nasopharynx should be as completely evaluated as possible in every cat with upper respiratory
signs. Caudal rhinoscopy (of the nasopharynx) is performed initially, either with a flexible endoscope retroflexed around
the soft palate or by use of a dental mirror inserted into the oropharynx while the soft palate is being retracted cranially.
Examination of this region may reveal mucus exudation, a foreign body or mass lesion, or nasopharyngeal stenosis, a fibrous
scar across the nasopharyngeal region that restricts nasal air-flow.
If a mass lesion is detected in the caudal nasopharynx, a biopsy can be obtained using a flexible endoscope, although it is
sometimes challenging to retroflex the endoscope and biopsy instrument into the small nasopharyngeal region of a cat. It is
generally wise to examine and biopsy the rostral nasal cavity before attempting a biopsy of the caudal nasopharynx, so that
bleeding does not obscure the nasal cavity. Rostral rhinoscopy can be achieved using either rigid arthroscopic equipment or
a semiflexible endoscope.
Cats with rhinitis display variable degrees of hyperemic mucosa, moderate to large amounts of mucoid to purulent discharge,
and irregular turbinate structures. Destructive rhinitis is evident as increased space between the turbinates and is typically
an indicator of long-standing or severe inflammation.
If white, yellow or black plaque lesions are seen in conjunction with destruction of turbinates, the possibility of Aspergillus
infection is considered. This can be confirmed by a biopsy of the plaque revealing septate hyphae. In contrast, the presence
of a mass lesion protruding between the turbinates should give rise to suspicion for neoplasia or cryptococcosis as a cause
for nasal signs. Nasal adenocarcinoma typically appears as a mass lesion, while nasal lymphoma may appear either as mass lesions
or a generalized mucosal infiltrate. In some cats, lymphoma may be found only in the nasopharynx as either a mass lesions
or as a diffuse mucosal infiltrate.