Page 285 - Small Animal Internal Medicine, 6th Edition

CHAPTER 15
VetBooks.ir

Disorders of the

Nasal Cavity

FELINE UPPER RESPIRATORY INFECTION chronic, persistent signs, most notably serous to mucopuru-
lent nasal discharge with or without sneezing. Chronic nasal
Etiology discharge can presumably result from persistence of an
Upper respiratory infections (URIs) are common in cats. active viral infection or from irreversible damage to turbi-
Feline herpesvirus (FHV), also known as feline rhinotrache- nates and mucosa by FHV; the latter predisposes the cat to
itis virus and feline calicivirus (FCV), cause nearly 90% of an exaggerated response to irritants and secondary bacterial
these infections. Bordetella bronchiseptica and Chlamydophila rhinitis. Unfortunately, correlation between tests to confirm
felis (previously known as Chlamydia psittaci) are less com- exposure to or the presence of viruses and clinical signs is
monly involved. Other viruses and Mycoplasmas (particu- poor (Johnson et al., 2005). Because the role of viral infec-
larly M. felis) may play a primary or secondary role, whereas tion in cats with chronic rhinosinusitis is not well under-
other bacteria are considered secondary pathogens. stood, cats with chronic signs of nasal disease are discussed
Cats become infected through contact with actively in the later section on feline chronic rhinosinusitis.
infected cats, carrier cats, and fomites. Cats that are young,
stressed, or immunosuppressed are most likely to develop Diagnosis
clinical signs. Infected cats often become carriers of FHV or Acute URI is usually diagnosed on the basis of history and
FCV after resolution of the clinical signs. The duration of the physical examination findings. Specific tests that are avail-
carrier state is not known, but it may last from weeks to able to identify FHV, FCV, Bordetella, Mycoplasma, and
years. Bordetella and M. felis can be isolated from asymp- Chlamydophila organisms include polymerase chain reac-
tomatic cats, although the effectiveness of transmission of tion (PCR), and virus isolation procedures or bacterial cul-
disease from such cats is not known. tures. PCR testing and virus isolation can be performed on
pharyngeal, conjunctival, or nasal swabs (using sterile poly-
Clinical Features ester swabs) or on tissue specimens such as tonsillar biopsy
Clinical manifestations of feline URI can be acute, chronic specimens or mucosal scrapings. Tissue specimens are
and intermittent, or chronic and persistent. Acute disease is usually preferred. Specimens are placed in appropriate trans-
most common. The clinical signs of acute URI include fever, port media. Routine cytologic preparations of conjunctival
sneezing, serous or mucopurulent nasal discharge, con- smears can be examined for intracytoplasmic inclusion
junctivitis and ocular discharge, hypersalivation, anorexia, bodies suggestive of Chlamydophila infection, but these find-
and dehydration. FHV can also cause corneal ulceration, ings are nonspecific. Although routine bacterial cultures of
abortion, and neonatal death, whereas FCV can cause oral the oropharynx can be used to identify Bordetella, the organ-
ulcerations, interstitial pneumonia, or polyarthritis. Rare, ism can be found in both healthy and infected cats. Regard-
short-lived outbreaks of highly virulent strains of calicivirus less of the method used, close coordination with the
have been associated with severe upper respiratory disease, diagnostic laboratory on specimen collection and handling
signs of systemic vasculitis (facial and limb edema progress- is recommended for optimal results.
ing to focal necrosis), and high rates of mortality. Borde- Tests to identify specific agents are particularly useful in
tella can cause cough and, in young kittens, pneumonia. cattery outbreaks in which the clinician is asked to recom-
Chlamydophila infections are commonly associated with mend specific preventive measures. Multiple cats, both with
conjunctivitis. and without clinical signs, should be tested when cattery
Some cats that recover from the acute disease have peri- surveys are performed. Test panels are commercially avail-
odic recurrence of acute signs, usually in association with able to probe specimens for multiple respiratory pathogens
stressful or immunosuppressive events. Other cats may have by PCR. Specific diagnostic tests are less useful for testing

257