Page 32 - Problem-Based Feline Medicine

24 PART 1 CAT WITH UPPER RESPIRATORY TRACT SIGNS

Pathogenesis ● Occasionally, central nervous system signs occur,
e.g. seizures, circling, ataxia, behavioral change.
Neoplasia may involve primarily the external nares,
– Signs may be present for days, or in rare cases,
the nasal cavity or the paranasal sinuses.
for as long as 2 years. Usually, signs are present
● Neoplasia typically causes purulent nasal dis-
for less than 6 months prior to diagnosis.
charge, bleeding, sneezing and/or obstruction.
Neoplasia involving primarily the external nares is Diagnosis
most commonly squamous cell carcinoma. Less fre-
quently fibrosarcoma or fibroma are involved. Cytological examination of an impression smear, or
● Squamous cell carcinoma usually occurs in older biopsy and histological examination of the lesion is
cats with a non-pigmented nose, that live in a sunny usually diagnostic for squamous cell carcinoma of the
climate and are outside during the day. external nares.
Neoplasia primarily involving the nasal cavity or the Intranasal tumors require a more invasive approach.
frontal sinuses is most commonly adenocarcinoma Cytological examination of the discharge or atraumatic
and lymphoma. nasal flush usually reveals evidence of inflammation
● Less common tumors are undifferentiated carci- (neutrophils and bacteria) but no tumor.
noma or sarcoma, olfactory neuroblastoma, ● Radiography demonstrates increased opacity of
fibrosarcoma, chondrosarcoma, chondroma, the nasal cavity and often destruction of the
osteosarcoma and squamous cell carcinoma. turbinates, nasal septum, lateral bone and loss
of teeth adjacent to the lesion. Radiographic
Neoplasia usually occurs in older cats (> 8–10 years). changes are often unilateral or asymmetrical.

Most occur in the caudal third of the nasal passage. ● A traumatic flush using a stiff catheter and
syringe (e.g. cut-off dog urinary catheter) yields
better results than an atraumatic flush.
Clinical signs ● A biopsy is often required to obtain tissue for a

Squamous cell carcinoma involving the external nares histological diagnosis. Tissue may be obtained
may cause sneezing and a bloody nasal discharge. using biopsy forceps through the external nares or
● Lesions causing signs of nasal disease many consist via a rhinotomy.
of a bleeding ulcer on the nasal septum, or an
advanced erosive lesion on the external nares. Differential diagnosis
– Signs may be present for months or years.
Cryptococcosis can produce very similar signs to
Intranasal tumors are associated with the following intranasal tumors. However, 70% of cats with crypto-
signs: coccosis have either distortion of the bridge of the
● Chronic sneezing and snuffling, which progres- nose or a polyp-like mass visible projecting from the
sively worsen with time. nasal cavity.
● Purulent or bloody nasal discharge, which may ● Most have a positive Cryptococcus titer.
temporarily respond to antibiotics. ● Cats with cryptococcosis tend to be younger than
– The discharge may initially be unilateral and cats with neoplasia.
progress to bilateral involvement. ● Chronic bacterial infection of the nasal cavity sec-
● Snoring, snorting, inspiratory stridor, stertor or ondary to viral upper respiratory disease may produce
dyspnea from nasal obstruction. similar signs. However, signs are typically present for
● Facial distortion, e.g. elevation of bridge of nose longer, and only very rarely is there nasal distortion.
(Roman nose) or facial swelling.
● Epiphora (associated with obstruction of the
Treatment
lacrimal duct), or a bloody ocular discharge.
● Signs of retrobulbar pressure may be present, e.g. Treatment of squamous cell carcinoma involving the
exophthalmos and ocular deviation. external nares depends on the extent of local invasion.