Page 15 - Problem-Based Feline Medicine

2 – THE CAT WITH ACUTE SNEEZING OR NASAL DISCHARGE 7

Necrosis of epithelium occurs within 24–48 h of viral
INTRODUCTION
contact.
Signs occur 2 to 6 days after infection.
MECHANISM?
Secondary bacterial infection of lesions usually
Signs of acute sneezing or nasal discharge indicate
occurs, producing purulent ocular-nasal discharges.
inflammation of the nasal cavity, which in cats is
almost always the result of infection, usually viral or Osteolysis of the turbinate bones may occur.
associated with chlamydophilia or mycoplasma.
Virus may cause corneal necrosis resulting in keratitis,
ulceration, and occasionally corneal rupture and loss of
WHERE? the eye.
Nose (nasal cavity, paranasal sinuses). Concurrent infections with calicivirus, Chlamy-
dophila, Mycoplasma or Bordetella bronchiseptica are
common, and may alter the clinical signs.
WHAT?
Most cats (80%) with acute onset of sneezing or nasal Clinical signs
discharge have calicivirus or herpesvirus.
Earliest sign is paroxysms of sneezing.
DISEASES CAUSING ACUTE Severe conjunctivitis occurs, with tearing, photophobia
SNEEZING OR NASAL DISCHARGE and chemosis.
Severe ocular and nasal discharges occur which are ini-
FELINE RHINOTRACHEITIS VIRUS (FELINE tially serous, but progress rapidly to mucopurulent.
HERPESVIRUS-1), “RHINO” OR Discharge is typically more marked than with calicivirus.
“SNUFFLES” ***
Later, discharge and crusting of nares and conjunctiva
may produce nasal obstruction and sealing of the eyelids.
Classical signs
Anorexia, depression and pyrexia are common; dehy-
● Acute onset of sneezing, pyrexia, depression.
dration may occur.
● Marked discharge from eyes and nose, initially
serous but progressing to mucopurulent. Tracheal and bronchial inflammation may result in
● Severe conjunctivitis with chemosis and coughing and dyspnea, and occasionally bacterial
photophobia. pneumonia occurs in kittens.
● Corneal keratitis or ulcers in some cats.
Very rarely, ulceration on the nose or tongue occurs, but
● Generally less than 10–14 days duration.
this is much more frequent with calicivirus infection.
For more details of ocular changes see page 1212 (The Corneal involvement resulting in keratitis may occur 1–2
Cat With Ocular Discharge or Changed Conjunctival weeks later. Keratitis is visible as corneal cloudiness
Appearance) and page 1237 (The Cat With (edema and inflammation), and punctate or branching
Abnormalities Confined to the Cornea). ulcers, which may coalesce to large ulcers.
Corneal perforation and secondary bacterial infection
may result in destruction of the eye; this occurs more
Pathogenesis often in young kittens (ophthalmia neonatorium).
Herpesvirus causes an acute infection of the upper Herpesvirus keratitis often occurs in the absence of
respiratory tract, conjunctiva and cornea. signs of active upper respiratory tract infection.

Virus multiplication is temperature restricted, and Infection of the pregnant queen may lead to fetal
most lesions occur on cooler mucosal-epithelial sur- absorption, abortion, or kittens either born infected or
faces, e.g. nasopharynx, conjunctiva, turbinates. developing signs shortly after birth.