Page 29 - Problem-Based Feline Medicine

3 – THE CAT WITH SIGNS OF CHRONIC NASAL DISEASE 21

Careful history taking and physical examination help
INTRODUCTION
localize the lesion.
Examination of the oropharynex under anesthesia and
MECHANISM?
radiography aid localization and diagnosis.
Chronic nasal disease should be suspected when a cat
has any of the following signs for more than 3 weeks.
WHAT?
● Chronic sneezing or snuffling.
● Nasal discharge which may be mucoid, purulent The most common cause of chronic nasal disease is
or bloody. secondary bacterial infection following herpes or
● Signs of nasal obstruction, such as stertorous respi- calicivirus infection
ration (snoring), stridor (high-pitched whistling ● Less common causes are Cryptococcus and neoplasia.
indicating obstruction), dyspnea or mouth breathing. ● Foreign bodies are generally rare causes of
● Gagging. chronic nasal signs in cats.
● Facial distortion. – Grass in the nasopharyngnx is more common,
● Nasopharyngeal distortion or bulging of the soft and causes gagging.
palate into the oral cavity.
Diagnosis is based on history and physical examination
The nasal mucosa responds to chronic disease by findings, radiography, Cryptococcus titer, and cytolog-
increased mucoid discharge. ical or histopathological examination of tissue samples.
● A purulent discharge occurs with infection or
necrosis.
● Blood may be present if there is severe inflamma- DISEASES CAUSING SIGNS OF
tion or erosion. CHRONIC NASAL DISCHARGE
– Bleeding without other signs of nasal disease,
such as a purulent nasal discharge, may indicate
SECONDARY BACTERIAL RHINITIS***
a systemic bleeding problem, rather than nasal
disease.
Classical signs
Facial distortion occurs with neoplasia or chronic
● Chronic sneezing and snuffling following
infection.
acute upper respiratory tract signs.
● Fungal (usually Cryptococcus) more often causes
● Chronic mucopurulent nasal discharge.
nasal distortion than chronic bacterial infection.
● Stertorous respiration.
Gagging occurs when there is nasopharyngeal stimu- ● Occasionally, nasal distortion.
lation from a mass lesion, a foreign body, or caudal
nasal discharge.
Ciliated columnar epithelium lining of the nasal cav-
Pathogenesis
ity undergoes squamous metaplasia after her-
pesvirus infection. Secondary bacterial infection of the nasal cavity and
● This decreases mucociliary clearance and predis- sinuses following feline herpesvirus or calicivirus
poses to secondary bacterial infection. infection is one of the most common causes of chronic
sneezing and nasal discharge in cats.
WHERE? Feline herpesvirus (feline rhinotracheitis virus) pre-
disposes to persistent or recurring bacterial infection
Signs of chronic nasal disease result from problems in
of the nose and sinuses.
any of the following sites:
● External nares, nasal cavity, frontal sinuses and Herpesvirus causes structural changes in the nose
nasopharynx. and sinuses.