Page 33 - Problem-Based Feline Medicine

3 – THE CAT WITH SIGNS OF CHRONIC NASAL DISEASE 25

● Radiotherapy, cryotherapy, intralesional chemo- found in soil contaminated by pigeon droppings, and in
therapy, or resection of the nasal planum are the debris of pigeon roosts.
indicated depending on the lesion.
Cryptococcus neoformans gattii is found in the develop-
● If ulcerated and erosive, radical resection of the
ing flower of Red River gums and forest red gums; high
nasal planum yields best results.
concentrations of organisms are found in the bark and the
Lymphoma is best treated with radiotherapy and/or accumulated debris surrounding the base of the tree.
chemotherapy. ● These trees have been widely exported around the
world from Australia.
Other tumors of the nasal cavity have a guarded to poor
prognosis. At the time of diagnosis, there is usually Organisms are viable for at least 2 years, if protected
extensive local invasion, and the recurrence rate after from direct sunlight and drying.
radiotherapy and/or surgery is high.
Nasal infection occurs via inhalation of airborne
organisms or contamination of the wound with organ-
Prognosis isms.
● There are no reports of transmission between ani-
Squamous cell carcinoma of the external nares can
mals or people; infection is from the environment.
have a good prognosis if the lesion is small, or if radi-
● Cell-mediated immunity may be compromised in
cal resection of the nasal planum totally removes the
infected animals; there are some reports of a
tumor. Local recurrence may occur, but the tumor is
higher incidence of FIV infection in cats with
slow to metastasize.
Cryptococcus.
Lymphoma has a guarded prognosis, but may respond ● Cats are more susceptible than dogs or humans.
to chemotherapy or radiotherapy. ● Any age of cat can be infected, but the average age
is 5 years (younger than cats with neoplasia).
Other intranasal tumors have a very poor prognosis,
● Following inhalation, the organism deposits in the
especially if destruction of the turbinates is evident
upper respiratory tract producing nasal granu-
radiographically.
lomas, or deposits in the alveoli producing pul-
monary granulomas, which are usually subclinical.
● The organism may disseminate through the crib-
CRYPTOCOCCOSIS*–**
riform plate or via the blood to the central nervous
system (CNS).
Classical signs
● If CNS signs develop, cats may or may not have con-
● Chronic nasal discharge and sneezing, current signs of respiratory infection.
progressing in severity.
In cats with cryptococcosis, 50–80% have respiratory
● Soft-tissue swelling over the nasal bones
disease involving mainly the nasal cavity, and 10–40%
(Roman nose), or polyp-like mass in nasal
have cutaneous or subcutaneous lesions. Central
cavity.
nervous system (CNS) involvement and ocular dis-
ease are less common.
Pathogenesis
Clinical signs
Cryptococcus neoformans most commonly produces
Upper respiratory tract signs are most common, and
granulomatous lesions in the nasal cavity or paranasal
include sneezing, snuffling and chronic nasal discharge.
sinuses.
● Nasal discharge may be unilateral or bilateral, and
Disease is caused by Cryptococcus neoformans neofor- serous, mucopurulent or hemorrhagic.
mans or Cryptococcus neoformans gattii.
Distortion and swelling over the bridge of the nose,
Cryptococcus neoformans neoformans is shed in or a polyp-like mass projecting from the nasal cavity
pigeon feces; high concentrations of organisms are are present in 70% of cats with the respiratory form.