Page 105 - Problem-Based Feline Medicine

7 – THE COUGHING CAT 97

Thoracic radiography improvement noted, slowly taper the dosage over several
● Interstitial or alveolar patterns with air bron- months. Serial radiographs are useful for long-term mon-
chograms, ranging from mild to severe. itoring. Many cases require long-term therapy for
● Nodular interstitial densities may mimic neoplas- months to years, at the minimum effective dosage.
tic masses. Dilated and truncated pulmonary arter-
Cytotoxic drugs – if large mass lesions are present
ies indicate potential heartworm disease or
(eosinophilic granulomatosis), more aggressive
pulmonary hypertension. Hilar lymphadenopathy
immunosuppression may be required. Cyclophos-
may be present.
2
phamide (50 mg/m PO q 48 h) has been used in con-
Cytology junction with prednisone. Azathioprine should be
● Method of sample acquisition is dependent upon avoided in cats due to toxicity.
the predominant radiographic pattern.
● Peribronchiolar or alveolar infiltrates may produce
Prognosis
excellent samples via airway wash (transtracheal or
bronchoscopic lavage). Eosinophilic inflammation can be very damaging to the
● Interstitial densities exfoliate poorly into the air- host tissues.
ways, and are better sampled via percutaneous
If identification and elimination of the offending aller-
lung aspirates.
gen is possible, the prognosis is excellent. If no allergen
● Cytology reveals a heavy infiltration of non-neo-
can be identified, the prognosis for cure is poor, but good
plastic eosinophils. Samples should be evaluated
to excellent control may be achieved with long-term
for the presence of antigens (parasites, fungal
therapy.
agents). Some neoplasms may be chemotactic to
eosinophils. Eosinophilic granulomatosis carries a poor long-
term prognosis, although remission of weeks to
Allied testing includes heartworm antigen or antibody
months is possible.
testing, fecal floatation and Baermann exams for para-
site ova and larvae, fungal culture (Cryptococcus spp.)
from lung fluid, and fungal serology.
Prevention
Parasite prevention programs.
Differential diagnosis
● Heartworm prophylaxis in endemic areas.
Pulmonary neoplasia may mimic the nodular infiltrates ● Routine anthelmintic treatments with pyrantel
radiographically. Cytology or lung biopsy is required pamoate or fenbendazole for nematodes such as
for differentiation. Toxocara cati and Aelurostrongylus spp.
● Limit exposure to intermediate hosts (i.e., crayfish
Congestive heart failure may also have alveolar infil-
for Paragonimus kellicotti).
trates, but usually other clinical signs (tachyarrhyth-
mias, murmurs, gallop rhythms) or radiographic signs Limit exposure to inhalant allergens. Clean the fur-
of heart disease such as cardiomegaly, pulmonary nace or air-conditioning air ducts, steam-clean carpets
venous congestion, pleural effusion are present. (avoiding perfumed cleansers), remove scented candles
or potpourri, avoid using hair spray or aerosol cleaners
Treatment near the patient, switch to dust-free and unscented cat
litter (clumping litters may be especially dusty), and
Treatment of the underlying disease is preferable, reduce exposure to cigarette smoke (quit or smoke out-
where possible (i.e., parasiticide therapy with fenben- side), high-efficiency in-home air filtration systems may
dazole for lungworm, praziquantel for lung flukes, reduce antigenic load.
etc.). Changing to a dust free cat litter and eliminating
Avoid exposure to cats with respiratory tract infec-
passive smoke from the environment may help.
tions, as PIE patients may be more prone to serious
Glucocorticoids – prednisone 1–2 mg/kg PO q 12 h for respiratory infections, especially if receiving
5–7 days. Repeat thoracic radiographs, and if there is immunosuppressive therapy.