In this lecture, we will briefly review two cases of cardiac neoplasia in cats and how tumours of the heart differ in cats compared to dogs.

Whereas in dogs, cardiac neoplasia typically presents as effusive pericardial disease, cats tend to have less obvious signs of cardiac compromise. Clinical signs are often less specific, which can lead to late or missed diagnosis.

Cardiac Neoplasia Seen in Cats

• Lymphoma; nodular or infiltrative (associated with FeLV infection in some cases)
• Chemodectoma (handful of case reports)
• Haemangiosarcoma (one case reported)
• Metastasis of extracardiac tumours; pulmonary and mammary adenocarcinomas reported

Lymphoma makes up at least 80% of identified cardiac tumours. Most cases have a pericardial effusion, and diagnosis is straightforward because the lesion tends to exfoliate and effusion cytology is diagnostic. However, this relies upon the clinician identifying a suspicion of lymphoma—the myocardium often appears thickened with abnormal relaxation, indistinguishable from hypertrophic cardiomyopathy, which is far more common in cats. If cardiac tamponade is identified in a cat, pericardiocentesis should be performed and submitted for cytology, as lymphoma is one of the very few causes of true cardiac tamponade in cats (where signs of right heart failure are present secondary to the pericardial fluid).

Case Examples

Cardiac Lymphoma

• 9-year old male Maine Coon cat, presented with signs of left-sided congestive heart failure.
• Echocardiographic evidence of LV hypertrophy and reduced function.
• Small pericardial effusion, suspected to be secondary to heart failure.
• Treated for congestive heart failure, positive clinical response for 4 weeks.
• Progressive weight loss, evidence of acute kidney injury, anorexia.
• Euthanasia performed and diagnosis of myocardial and renal lymphoma evident on histopathology.
• Particularities of the disease and a literature review will be discussed.

Heart Base Tumour

• Seven-year-old female domestic shorthair cat, presented with signs of increased respiratory effort.
• Radiographic evidence of mass at the heart base.
• Cytology with ultrasound guidance of cardiac mass showed evidence of a neuroendocrine tumour.
• CT imaging showed bronchial obstruction.
• Bilateral bronchial stents deployed via minimally invasive technique.
• Clinical signs relieved for some months, until tumour invaded oesophagus and patient euthanised because of regurgitation.