Abstract
Dear Editors, — In their excellent review article on pleural effusion in the cat, 1 Beatty and Barrs quite correctly state that … ‘The importance of gentle handling of cats in respiratory distress cannot be overemphasised,’ and then suggest a series of examinations, some of which (eg, clipping the neck hair to check for jugular distension/pulsation) may be sufficiently distressing to trigger further respiratory decompensation. My experience from working in both general practice and emergency clinics is that the less these patients are handled — however gently — the better.
An almost pathognomonic diagnostic feature of a pleural effusion sufficient to cause severe respiratory distress is hepatic retropulsion, often of a normal-sized liver. This can be quickly and easily assessed in a distressed patient by very gentle palpation in the time that it takes to effect a transfer to an oxygen cage. Once a high index of suspicion for a pleural effusion has been established with minimal handling, then, after a period of patient re-oxygenation, it is reasonable to proceed directly to a diagnostic and/or therapeutic thoracocentesis — thus reducing the patient's distress and creating safer conditions for further diagnosis.
The major differential would be hepatomegaly, which tends to be characterised by rounded edges to the liver lobes that can sometimes be inferred during this brief examination. However, hepatomegaly per se is an unusual cause of respiratory distress unless associated with conditions that can also produce pleural effusions, such as congestive heart failure.
Although I have no hard figures, my overall impression is that hepatic retropulsion in a cat with dyspnoea (especially if that dyspnoea is inspiratory, allied to no other signs consistent with upper airway obstruction) has a high sensitivity and specificity (>90%). Ideally, this should be confirmed with an appropriate prospective study: accrual and analysis of data should be relatively simple and may provide an evidential base for the diagnostic/treatment protocol outlined above.