Ultrasonographic appearance of normal superficial cervical and subiliac lymph nodes in cattle.

The superficial cervical and the subiliac lymph nodes of 18 healthy, non-pregnant Simmental cows with a mean (sd) age of 5-6 (1.6) years were examined ultrasonographically in transverse and longitudinal planes with a real-time B-mode unit equipped with a 7.5 MHz linear-transducer. The position, demarcation and echogenicity of the lymph nodes were examined, and the craniocaudal and lateromedial diameters of each lymph node were measured three times within a period of six weeks. The pole to pole length of the lymph nodes was determined with a tape measure on the surface of the skin because the whole length could not be imaged in a single scan field. The gross anatomical and histological results showed that the lymph nodes were normal. Ultrasonographically, they were well demarcated from the adjoining muscular and subcutaneous tissue. Their internal structure was characterised by an anechoic to hypoechoic cortical zone corresponding to the lymphoid tissue, and an echogenic medullary zone, where the lymphatic sinuses converge towards the hilus and produce numerous acoustic interfaces. In all the lymph nodes, the hilar area had an echoic to hyperechoic appearance. The mean (sd) pole to pole length of the superficial cervical lymph nodes was 15.5 (3.2) cm and of the subiliac lymph nodes 13.5 (2.4) cm. The mean craniocaudal and lateromedial diameters of the superficial cervical lymph nodes were 2.8 (0.3) cm and 1.6 (0.3) cm, and those of the subiliac lymph nodes were 2.4 (0.4) cm and 1.1 (0.3) cm. The ultrasonographic morphology of these normal lymph nodes was consistent and provides basic reference data for the investigation of lymphadenopathies in cattle.