Clinical Picture

The juvenile or calf form of lymphosarcoma is seen mostly in animals up to six months of age, but occasionally calves are congenitally infected. The most frequent abnormalities observed are swollen superficial lymph nodes. The swellings are generally symmetrical, with the nodes being firm, smooth, mobile, and painless. There is also enlargement of lymph nodes which are not normally palpable, such as the parotid, deep cervical and popliteal nodes. Enlargement of the medial iliac node (detected by rectal palpation) is relatively common. Ulceration of the skin over the lymph nodes is not seen. Heart and respiratory rates are increased. Coughing and harsh respiratory sounds are common. Occasionally animals may have a fever, diarrhoea, ruminal tympany or liver enlargement.

The thymic form is mostly seen in animals 6 months to two years of age. Loss of condition and/or the development of a swelling in the neck (pre-sternal area) is usually seen. Palpation reveals a firm mass that may or may not be surrounded by oedema. Distension of the jugular veins is usually present but pulsation is rare. Increased heart and respiratory rates are occasionally seen, as well as coughing, straining and a temperature rise.

The skin form is relatively rare and occurs in cattle 1.5 to 3 years old. There are numerous tumours in various parts of the skin, about 5-10 cm in diameter. Some lymph nodes and internal organs may also be involved.

Occasionally, juvenile and cutaneous forms regress and disappear but they are usually fatal. Cases of juvenile and thymic forms of lymphosarcoma are usually sporadic lymphosarcoma and not EBL.

The adult form of lymphosarcoma occurs in animals over 3 years of age. Animals suddenly become ill, lose condition over a period of weeks or months before death occurs. Occasionally animals die suddenly due to rupture of a tumorous spleen or abomasum.

The clinical signs vary enormously, depending on which organ system is most affected. Clinical syndromes seen include paresis due to a tumour in the spinal cord, heart disease due to a tumour in the heart, respiratory distress due to a tumour in the retropharyngeal nodes. There is usually an enlargement of various superficial and internal lymph nodes in addition to the main presenting clinical signs.

Generally there is a persistent lymphocytosis prior to the development of lymphosarcoma. It usually commences when the animal is at least 2 years of age and persists until death. Provided only persistent lymphocytosis is present, production performance is not affected.