Page 412 - WSAVA2018
P. 412

 25-28 September, 2018 | Singapore
for aerobic and anaerobic culture, fungal culture, or PCR (e.g. for Mycoplasma or Bordetella).
· Endoscopic examinations are performed next with the anaesthetised cat in sternal recumbency. Avoid mouth gags that maximally open the mouth as these occlude maxillary artery blood flow and can cause post-an- aesthetic cortical blindness. Nasopharyngoscopy using a retroflexed bronchoscope or similar scope is performed to detect choanal mass lesions, stenotic le- sions or foreign bodies. Mass lesions can be biopsied. Rigid antegrade rhinoscopy is performed next.
· Nasal lavage and nasal biopsy. Guided endoscopic or unguided nasal biopsies are collected for culture and histology. Therapeutic nasal lavage alleviates congestion in cats with CRS and is performed in the intubated cat (cuffed tube) with the pharynx packed with gauze. A 10 ml aliquot of sterile saline is flushed into the nasal cavity through one naris while the other naris is occluded with digital pressure. The procedure is repeated on the other side, and the gauze is then retrieved to inspect for foreign bodies, fungal plaques or tissue remnants. Nasal tumours, especially lympho- mas, are friable and the nasal flush may yield tissue fragments for histopathology. Prior to extubating the cat, the pharynx should be suctioned carefully.
· Histology of nasal mucosal biopsies is essential to distinguish CRS from neoplasia and fungal infection. Inflammatory infiltrates in CRS can be neutrophilic, lymphoplasmacytic, eosinophilic or mixed and may be accompanied by epithelial erosions, turbinate lysis/remodelling, fibrosis, necrosis and glandular hyperplasia. Special stains to detect fungal hyphae such as PAS should be requested. If eosinophilic infiltrates are present and fungal stains are negative, immunohistochemistry for FHV may be performed.
Management of CRS
Treatment is palliative. Antibiotic therapy is guided by susceptibility results or given empirically for 6
– 8 weeks using clindamycin, doxycycline, amox- icillin-clavulanate or azithromycin. Longer-term or intermittent therapy may be required. Use of nasal decongestants should be limited to three days be- cause rebound vasodilation can exacerbate signs. Famciclovir controls signs in some cats using 90 mg/kg q 12 h PO for one week beyond resolution of clinical signs.Management of nasal cryptococcosis Fluconazole is first-line therapy and is usually re- quired for at least several months. Itraconazole is also effective but has more adverse effects (Table 1). In severe disease combination therapy with ampho- tericin B and flucytosine is recommended for four weeks followed by azole monotherapy. Treatment
is continued until the cryptococcal antigen latex as- say titre is zero, with follow-up antigen testing one month after therapy has been stopped. The prog- nosis for resolution of infection is good (>75% suc- cessful), although relapses occur in 17% of cases. Aspergillosis
Endoscopic removal of all visible fungal plaques
combined with 1% topical clotrimazole infusion is recommended for SNA and prognosis is general-
ly favourable. For SOA the prognosis is generally poor, although individual cases have been cured. Posaconazole monotherapy or combined with terbinafine is recommended for first-line therapy but treatment should be guided by the results of anti- fungal susceptibility testing (Table 2). Itraconazole should not be used empirically because resistance is common.Management of nasal neoplasia
Both radiation and chemotherapy have benefits
in treating nasal lymphoma. B-cell lymphomas, the most common type of nasal lymphoma, respond well to radiation therapy and have the best prog- nosis. In one study of 97 cats with nasal lymphoma treated with radiation therapy (RT) alone, chemo- therapy alone or RT + chemotherapy. The median survival time for all therapies was 473 days and was not significantly different for the different treatment modalities.
TABLE 2 Dosages of Antifungals Used in the Treatment of Fungal Rhinitis
  Dosage/Route of Administration
   Adverse Effects
 2.5-10 mg/kg q12h PO or 50 mg per cat q12-24h
  Inappetence Hepatotoxicity (rare)
5 mg/kg q12h or 10 mg/kg q24h PO. Administer with food
Oral suspension: 3 mg/kg q24h PO
  C, A
 Anorexia, vomiting
Hepatotoxicity: elevated liver enzymes, jaundice.
  15 mg/kg PO loading dose, then 7.5 mg/kg q 24h
Administer with food
  C, A
   Hepatotoxicity: infrequent compared to itraconazole
12.5 mg per cat q 72h PO
Blindness, ataxia, stupor
Consider use when other therapies have failed.
  30 mg/kg q24h PO
   Anorexia, vomiting, diarrhea
 50 mg/kg q8h PO or 75 mg/kg q12h PO
     Anorexia, vomiting, diarrhea
   Amphotericin-B deoxycholate
0.5 mg/kg of 5 mg/ml stock solution in 300 ml per cat of 0.45% NaCl + 2.5% dextrose SC 2 -3 times weekly to a cumulative dose of 10-15 mg/kg
  C, A
 Nephrotoxicity: Monitor urea/creatinine. Discontinue for 2 to 3 wks if azotaemic.
 Liposomal amphotericin
 1-1.5 mg/kg IV q48h
Give as a 1 mg/ml solution in 5% dextrose by IV infusion over 1-2 h
 C, A
  Nephrotoxicity: Monitor urea/creatinine every 2-3 days during administration.
  Loading dose 1 mg/kg IV, then 0.75 mg/kg q 24h IV
  A, Aspergillosis; ALP, alkaline phosphatase; ALT, alanine aminotransferase; C, cryptococcosis; PO, orally.
Johnson LR, Barrs VR. Rhinitis in Cats. Kirk’s Current Veterinary Therapy XV 2015, Ed: Bonagura JB, Else- vier Saunders, Chptr 155, pp 2014.

   410   411   412   413   414