Thoracic neoplasia in equids: 35 cases (1967-1987).

Thirty-two horses and 3 ponies had neoplasia involving the thoracic cavity. Lymphosarcoma of the thorax was found in 19 (54.2%) of the equids. The other 16 equids had metastatic adenocarcinoma (7 horses; 20%), metastatic squamous cell carcinoma (5 equids; 14.3%), metastatic hemangiosarcoma (3 equids; 8.6%) or undifferentiated sarcoma (1 horse; 2.9%). Thoracic neoplasia was diagnosed before death in 15 equids (42.9%).