Page 296 - Small Animal Internal Medicine, 6th Edition

268 PART II Respiratory System Disorders

response is not seen, the antibiotic is discontinued. Note that IDIOPATHIC CANINE CHRONIC
frequent stopping and starting of different antibiotics every (LYMPHOPLASMACYTIC) RHINITIS
VetBooks.ir 7 to 14 days is not recommended and may predispose the cat Etiology
to resistant gram-negative infections. Cats that respond well
Idiopathic chronic rhinitis in dogs is sometimes character-
during the prolonged course of antibiotics but that relapse
shortly after discontinuation of the drug despite 4 to 6 weeks ized by the inflammatory infiltrates seen in nasal mucosal
of relief are candidates for continuous long-term antibiotic biopsy specimens; thus the disease lymphoplasmacytic rhi-
therapy. Treatment with the previously used antibiotic often nitis has been described. It was originally reported to be
can be successfully reinstituted. Amoxicillin administered a steroid-responsive disorder, but a subsequent report by
twice daily is often sufficient. Windsor et al. (2004) and clinical experience suggest that
Treatment with famcyclovir may be effective in cats with corticosteroids are not always effective in the treatment of
active herpesvirus infection, as discussed in the section on lymphoplasmacytic rhinitis. It is not uncommon for neu-
feline URIs earlier in this chapter. Anecdotal success in occa- trophilic inflammation to be found, predominantly or along
sional cats has been reported with treatment with the second- with lymphoplasmacytic infiltrates. For these reasons, the
generation antihistamine cetirizine, as described previously less specific term idiopathic canine chronic rhinitis will
for allergic rhinitis. be used.
Cats with severe signs that persist despite the previously Many specific causes of nasal disease result in a con-
described methods of supportive care may benefit from glu- current inflammatory response because of the disease itself
cocorticoids to reduce inflammation. However, certain risks or as a response to the secondary effects of infection or
are involved. Glucocorticoids may further predispose the cat as an enhanced response to irritants; this makes a thor-
to secondary infection, increase viral shedding, and mask ough diagnostic evaluation of these cases imperative.
signs of a more serious disease. Glucocorticoids should be Windsor et al. (2004) performed multiple PCR assays on
prescribed only after a complete diagnostic evaluation has paraffin-embedded nasal tissue from dogs with idiopathic
been performed to rule out other diseases. Prednisolone is chronic rhinitis and failed to find evidence for a role of
administered orally at a dose of 0.5 mg/kg q12h If a ben- bacteria (based on DNA load), canine adenovirus-2, para-
eficial response is seen within 1 week, the dose is gradu- influenza virus, Chlamydophila spp., or Bartonella spp. in
ally decreased to the lowest effective dose. A dose as low as affected dogs. Large amounts of fungal DNA were found
0.25 mg/kg every 2 to 3 days may be sufficient to control in affected dogs, suggesting a possible contribution to
clinical signs. If a clinical response is not seen within 1 week, clinical signs. Alternatively, the result may simply reflect
the drug should be discontinued. As discussed with aller- decreased clearance of fungal organisms from the diseased
gic rhinitis, administration of glucocorticoids via metered nasal cavity.
dose inhaler may be effective in cats responsive to oral Although not supported in the previously quoted
glucocorticoids. study, a potential role for Bartonella infection has been
Other drugs with potential antiinflammatory effects that suggested on the basis of a study that found an associa-
may provide relief include azithromycin (described with tion between seropositivity for Bartonella spp. and nasal
antibiotics), piroxicam, and leukotriene inhibitors. Omega-3 discharge or epistaxis (Henn et al., 2005) and a report of
fatty acid supplementation may also serve to dampen the three dogs with epistaxis and evidence of infection with
inflammatory response. Effectiveness of these treatments in Bartonella spp. (Breitschwerdt et al., 2005). A study con-
cats with chronic signs is based on anecdotal reports of ducted in our laboratory (Hawkins et al., 2008) failed to
success in individual cats. Remember that piroxicam should find an obvious association between bartonellosis and idio-
not be given concurrently with corticosteroids. pathic rhinitis, in agreement with findings by Windsor et al.
Cats with severe or deteriorating signs that persist despite (2004).
conscientious care are candidates for turbinectomy and
frontal sinus ablation, if a complete diagnostic evaluation to Clinical Features and Diagnosis
eliminate other causes of chronic nasal discharge has been The clinical features and diagnosis of idiopathic canine
performed (see Chapters 13 and 14). Turbinectomy and chronic rhinitis are similar to those described for idio-
frontal sinus ablation are difficult surgical procedures. Major pathic feline chronic rhinosinusitis. Chronic mucoid or
blood vessels and the cranial vault must be avoided, and mucopurulent nasal discharge is the most common clini-
tissue remnants must not be left behind. Anorexia can be a cal sign and is typically bilateral. Fresh blood may be
postoperative problem; placement of an esophagostomy or seen in the discharge of some dogs, but it is not usually a
gastrostomy tube serves as an excellent means of meeting primary complaint. Given that it is an idiopathic disease,
nutritional requirements if necessary after surgery. Complete the lack of specific findings is important. Dogs should have
elimination of respiratory signs is unlikely, but signs may be no funduscopic lesions, no lymphadenopathy, no facial or
more easily managed. The reader is referred to surgical texts palate deformities, and healthy teeth and gums. Anorexia
for a description of surgical techniques (e.g., see Fossum in and weight loss are rarely reported. Thorough diagnostic
Suggested Readings). testing is indicated, as described in Chapters 13 and 14.