Cats with respiratory distress represent a significant diagnostic and therapeutic challenge to the small animal veterinarian.
The most common causes of feline respiratory distress are pulmonary edema, pleural effusion, asthma, and neoplasia. Available
methods to try to elucidate the etiology of an individual cat's respiratory distress include evaluation of historical and
physical examination findings, thoracic radiography, cytology and ultrasonography or echocardiography. Additionally, it is
important to distinguish respiratory distress that is a presenting complaint from respiratory distress that develops during
hospitalization for another problem and to quantify distress as mild, moderate, severe or immediately life-threatening.
Respiratory distress at presentation
Respiratory distress as a presenting complaint is a common condition for the emergency feline practitioner. Additionally,
it is well-recognized that cats with respiratory difficulty are challenging to treat, as these cats create a large amount
of anxiety in many veterinarians, due to fears of either excessive stress associated with therapy or difficulty with determining
the underlying diagnosis.
Pertinent historical findings may include a previous diagnosis of heart or lung disease. Many owners recall a prior diagnosis
of a heart murmur, or past episodes of coughing which may suggest airway disease. Additionally, while cats have a lower incidence
of traumatic pulmonary contusion or pneumothorax than dogs, access to the outdoors may support a traumatic etiology. Other
factors, such as signalment and progression of clinical signs are less frequently helpful, although hypertrophic cardiomyopathy
is more common in male cats and the Siamese breed has a reportedly higher incidence of airway disease.
Physical examination findings are often helpful in determining the cause of feline respiratory distress. The body temperature
is frequently subnormal in cats with heart disease, but is generally normal or even elevated with pulmonary disease. Similarly,
an elevated heart rate (>200 bpm) is often associated with heart failure, while cats with primarily respiratory disease may
have a slower heart rate. However, cats who are hypothermic due to heart disease may be relatively bradycardiac as well.
The presence of a heart murmur, gallop rhythm or arrhythmias is strong evidence for cardiac disease. Jugular venous distension
may be present with heart disease, although some evidence suggests that jugular distension may accompany pleural effusion
of any etiology. The heart failure cat rarely presents with ascites. Crackles may be present with both pulmonary edema and
asthma. Diminished respiratory sounds, particularly ventrally, often signifies pleural effusion as does a significant abdominal
component to respiration. Cats with severe pleural effusion may occasionally appear to have upper airway obstruction.