Cardiac lymphoma in cats: when wall thickening is not HCM
10-year-old cat with a week of anorexia, weight loss and tachypnoea. The ECG shows second-degree AV block. Echocardiogram: hypoechoic, irregular, segmental thickening of the septum and RV free wall (up to 9 mm), other walls normal, moderate pericardial effusion and pleural effusion. Left atrium normal.
Which test is most useful to reach the diagnosis?
chevron_right Show answer and explanation
A. None: it is segmental HCM; treat with atenolol and furosemide
Hypoechoic, irregular thickening with effusions, AV block and a normal left atrium does not fit HCM. Labelling it so delays a treatment that may work.
B. NT-proBNP to confirm a cardiac origin
It may be raised by the myocardial involvement, but it does not distinguish neoplastic infiltration from cardiomyopathy.
C. Cardiac troponin I
It indicates cardiomyocyte injury and is usually raised, but it is non-specific: it does not identify the type of lesion.
D. Cytology of the pleural or pericardial effusion and, if inconclusive, ultrasound-guided aspiration of the lesion or other affected organs
Correct. Lymphoma is the most common cardiac neoplasm in cats and, unlike haemangiosarcoma, its cells exfoliate readily into effusions. Cytology is usually enough for diagnosis and allows chemotherapy to begin.
lightbulb Key takeaway
Suspect neoplastic infiltration with irregular, hypoechoic or asymmetric myocardial thickening, especially with effusions, arrhythmias or conduction blocks and systemic signs. Look for lymphoma in other organs (mediastinum, kidney, intestine) and test for FeLV.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.