Cats with moderate and severe inflammation may also appear relatively normal on rhinoscopy indicating a need to perform biopsies
in cats to assess the severity and type of inflammation. Biopsies may show primarily neutrophilic, lymphocytic or pleiocellular
inflammation in cats with chronic nasal signs. Typically, nonspecific histopathologic lesions such as fibrosis, necrosis,
turbinate remodeling and glandular hyperplasia are present in addition to inflammation.
Nasal biopsy specimens can be collected for bacterial culture and may be helpful in guiding antibiotic therapy for secondary
bacterial rhinitis. PCR evaluation of nasal biopsy or flush samples for Mycoplasma species appears to correlate with isolation
of the organism on culture, provides a result much more quickly than standard culture techniques, and can detect non-cultivable
species of Mycoplasma.
During rhinoscopy, it is helpful to flush and aspirate as much mucus from the nasal cavity as possible. Any isotonic fluid
solution can be used. If flushing is performed in a rostral to caudal manner, the cuff on the endotracheal tube should be
fully inflated to a level that blocks fluid without inducing tracheal trauma, and the oropharynx should be gently packed with
lap pads to avoid tracheal aspiration of fluid. It would be safer to place a Foley catheter in the caudal nasopharynx and
flush fluid from in a caudal to rostral direction. Removal of secretions from the nasal cavity usually aids in temporary improvement
in clinical signs.
Treatment of rhinitis
Cats with acute or chronic rhinitis are usually treated with broad-spectrum antibiotics in an attempt to control secondary
bacterial proliferation in the nasal cavity. Cats with acute disease generally improve rapidly, sometimes even before antibiotic
therapy has time to be effective. Cats with chronic disease usually demonstrate an initial response to antibiotic therapy,
and a positive response may be an indication to initiate chronic (six to eight weeks or longer) antibiotic treatment. Commonly
used antibiotics include doxycycline, cephalexin, amoxicillin-clavulanic acid or clindamycin.
Enrofloxacin or marbofloxacin may be useful, and use of azithromycin is becoming popular in cattery and breeder situations
because the pharmacokinetics allows twice weekly dosing. Intermittent or suppressive antibiotic therapy may be helpful in
some instances, but resistance to antibacterial action occurs commonly.
Antiviral therapy is rarely employed in cats with chronic rhinosinusitis because of failure to achieve definitive documentation
of viral involvement and concern about potential side effects of antiviral therapy.
Currently, it is safe to use lysine as an antiviral agent at 500 mg PO BID. This amino acid replaces arginine in viral proteins
rendering them nonfunctional and reducing viral replication. Lysine therapy is generally safe to use in young or older animals
with acute or chronic rhinitis.
Steroids may reduce mucus production, and treatment may improve the cat's attitude or appetite. An alternative to steroid
therapy is the use of piroxicam. This agent is generally well tolerated by cats at a dosage of 0.3 mg/kg PO daily or every
other day, and some cats experience alleviation in clinical signs.
Because this drug is supplied in 10 mg capsules, the appropriate dosage for a cat must be specially prepared by a compounding
pharmacy. Side effects include anorexia, vomiting and diarrhea.
Occasionally, cats will tolerate local instillation of isotonic fluid solution drops in the nasal cavity. This stimulates
a sneeze response and encourages evacuation of mucus. In some cases, intermittent flushing of the nasal cavity under anesthesia
(with tracheal intubation) can be useful in controlling clinical signs. Individual cats may show improvement with antihistamines
or systemic decongestants; however, these drugs should be used cautiously in cats. Topical decongestants are often recommended
for alleviation of serous nasal discharge in acute rhinitis, but it seems unlikely that these are effective in the presence
of purulent nasal discharge.
Owners should be informed that cats with chronic rhinosinusitis have a guarded prognosis. Clinical signs of sneezing and mucopurulent
discharge are difficult to control and impossible to eradicate. Signs may abate somewhat with long-term antibiotic, anti-inflammatory
and other adjunct therapies but signs of rhinosinusitis virtually always recur.
Surgical therapy can be offered when medical therapy fails to control signs to a reasonable extent. Frontal sinus ablation
can be effective in controlling clinical signs. Sneezing and nasal discharge may not be totally obliterated with this technique;
however, substantial improvement can be seen in some cases. This procedure may be associated with complications such as intraoperative
hemorrhage and persistent anorexia due to loss of smell.
What's your question?
Send your pediatric/geriatric related questions to: Pediatric/Geriatric Protocol, DVM Newsmagazine, 7500 Old Oak Blvd., Cleveland,
OH 44130. Your questions will be answered by Dr. Hoskins in upcoming columns.