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

This research article documents a case study, depicting the detection and management of a rare form of heart tumor known as Primary Cardiac Lymphoma in a 10-year-old horse. The tumor was characterized by unusual symptoms, diagnosis, and conditions previously unreported in equine case studies making this rare equine lymphoma case a noteworthy addition to veterinary literature.

Case Description and Symptoms

The equine patient was a 10-year-old horse, showing signs of general weakness, weight loss, and decreased appetite. Clinically, the horse exhibited abnormal medical conditions such as a high heart rate (tachycardia), heart murmurs, abnormal breathing pattern (tachypnoeaic) along with muscular weakness and twitching.

• The heart rate was confirmed through electrocardiography.
• Heart murmurs were detected through auscultation.
• There was no indication of any neurological disease.

Medical Examination and Findings

On conducting further diagnostic tests, two-dimensional and M-mode echocardiography found increased contractility and considerable thickness in the heart divisions (interventricular septum & left ventricular free wall).

• The myocardium displayed a heterogeneous appearance along with a distinct intramyocardial vasculature.
• A presumed irregular mass was identified circling the aorta and stretching from the interventricular septum. The coronary artery was also notably enlarged.
• However, no further irregularities were noticed within the abdominal cavity or lesions within the mediastinal, pleural, or pulmonary regions via thoracic ultrasound.

Bloodwork findings included leucocytosis, higher fibrinogen levels, hypoalbuminia, hyperglobulinemia and a slightly elevated lactate and ionized calcium level. Blood gas analysis showed normal oxygenation, and cardiac troponin I concentrations were within normal limits.

Decision and Postmortem Findings

Due to the severe prognosis, unlikelihood of a response to therapy and expected deterioration of the horse’s condition, the decision to euthanize the horse was taken. Postmortem examination showed a lesion located at the aorta base, hard plaques along the aorta, and both coronary arteries. Histopathological examination confirmed that the disease was T cell-rich B cell lymphoma.

Comparison with Previously Reported Cases

The presentation and occurrence of mitral valve regurgitation in this case showed similarities to previous cases of Primary Cardiac Lymphoma cases in other species. However, no pericardial effusion was found as reported in some earlier cases. The origin of the majority of equine lymphoma cases is subject to debate, with some studies suggesting primarily a B cell origin, while others indicating a T cell origin. The postmortem findings and histopathological appearance in this case correlated with descriptions in existing literature.