Page 93 - Problem-Based Feline Medicine

6 – THE CAT WITH HYDROTHORAX 85

● Transesophageal ultrasonography is excellent for
PLEURAL/MEDIASTINAL MASSES
demonstrating mediastinal masses, but requires
specialized equipment and general anesthesia.
Classical signs
● Surgical or ultrasound-guided biopsy of the mass
● Muffled heart and lung sounds ventrally. may be required for a definitive diagnosis.
● Dyspnea characterized by excessive chest
Thoracocentesis and analysis of the fluid may be diagnos-
excursions with poor airflow.
tic if the neoplasm has exfoliated into the fluid. This is,
● Orthopnea (positional dyspnea with
however, a rare occurrence. Typically the fluid is a modi-
reluctance to lie in lateral recumbency).
fied transudate, although occasionally it is an exudate.
See main reference on page 56 for details (The Dysp- Mediastinal lymphoma may have hypercalcemia as a
neic or Tachypneic Cat). paraneoplastic syndrome, but this is rare in the cat.
Tissue biopsy and histopathology are required for
Clinical signs definitive diagnosis.

Mediastinal masses are often thymomas, thymic
Differential diagnosis
lymphoma or mediastinal lymphoma. Occasionally,
ectopic thyroid adenocarcinoma may create a space- Other causes of pleural effusion that typically cause a
occupying mass of the mediastinum. Pleural masses modified transudate are cardiac disease and other air-
include mesotheliomas, osteosarcoma or chondrosar- way neoplasias. Radiography and ultrasound can usu-
coma of the ribs or sternabrae. ally differentiate these.
Signs are related to the space-occupying nature of the
mass, or to obstruction of lymphatic drainage and sec- Treatment
ondary pleural effusion.
Lymphoma of the thymus or mediastinal lymph nodes
Signs include increased dyspnea in lateral recum- is best handled with standard chemotherapy protocols
bency (i.e., orthopnea), tachypnea, minimal airflow for lymphoma (see page 676).
with increased chest excursions, muffled heart and
Surgical excision is the treatment of choice for thy-
lung sounds or asymmetrical sounds if the heart is
moma, and may be curative.
displaced laterally.
Mesothelioma is an infiltrative disease that cannot be
Extraluminal compression of the trachea can cause
readily resected, and there are few reports in the litera-
dyspnea and cough.
ture of effective chemotherapy. Local infusion of car-
Compression of the anterior thorax may reveal boplatin may be helpful with or without the addition of
decreased compliance. doxirubicin intravenously. Prognosis is grave.

PNEUMONIA
Diagnosis
Thoracic radiography may reveal the mass lesion or Classical signs
the secondary pleural effusion.
● Moist, productive cough, with adventitial
● Separation of the “cupolae” (anterior tips of the cra-
lung sounds.
nial lobes) on ventrodorsal projection, representing
● Fever.
widening of the anterior mediastinum, may be a
● Fetid halitosis.
sensitive indicator of a subtle mass lesion.
● Parapneumonic pleural effusion can create
Thoracic ultrasound can be extremely useful. dyspnea and decreased ventilation,
● Small mediastinal masses surrounded by aerated possibly with exaggerated chest
lung may not be visible from a paracostal approach, excursions/poor airflow.
and may require a thoracic inlet window.
continued