Primary cardiac lymphoma in a 10-year-old equine gelding

PRIMARY cardiac lymphoma (PCL) is a rare tumour in all species (Sims and others 2003, Shinohara and others 2005, Miguel and Bestetti 2011, Petrich and others 2011) affecting the myocardium and/or pericardium (Shinohara and others 2005, Petrich and others 2011). PCL has been reported in cats, dogs and human beings, but prior case descriptions in horses were not identified in the literature. In horses, four categories of equine lymphoma are described: multicentric, thymic, alimentary and cutaneous (van den Hoven and Franken 1983) plus occasional anomalous cases (Meschter and Allen 1984, Staempfli and others 1988, Rhind and Dixon 1999, Taintor and Schleis 2011).

A 10-year-old Cob gelding was presented with lethargy, weight loss and anorexia. On initial assessment, the horse was quiet, dull but responsive. Clinical examination revealed sinus tachycardia (64 bpm), which was confirmed by electrocardiography. A grade IV/VI pansystolic decrescendo murmur and a grade II/VI holodiastolic murmur, both loudest over the left fourth intercostal space, were auscultated. Jugular pulse quality and filling, and capillary refill time and colour were normal. The horse was tachypnoeic (20 bpm) with bronchovesicular sounds over both hemithoraces, more so on the right-hand side. Rectal temperature was normal. Muscle fasciculations of the proximal forelimb and weakness were observed, but no proprioceptive deficits suggestive of neurological disease were noted.

Two-dimensional and M-mode echocardiography revealed normal cardiac dimensions with increased contractility (fraction shortening of 60 per cent; normal range 27 to 47 per cent) and …