Ultrasonography is an imaging technique universally employed in veterinary medicine. It has many advantages, such as high availability, non-invasiveness, short examination time, no anesthesia, and low cost, but also some drawbacks, like low specificity. To overcome these limitations, ultrasound contrast agents (UCAs) and specific ultrasound contrast techniques have been developed. The application of UCAs and specific sonographic contrast techniques increase the specificity and sensitivity of ultrasound examination. Nowadays the new contrast-specific imaging techniques enable the separation of the linear tissue signal from the non-linear microbubble signal, which, combined with the introduction of second-generation UCAs, makes contrast-enhanced ultrasonography a very important diagnostic tool.
Contrast-enhanced ultrasonography is mainly used in heart examination and to detect and characterize focal liver lesions. CEUS also allows the evaluation of the spleen, pancreas, kidneys, lymph nodes and the detection of porto-systemic shunts. UCAs can be administered intracavitarily, e.g. in the urinary bladder. In human medicine CEUS is used in the assessment of anti-angiogenic treatment. In some cases concerning the detection and characterization of focal lesions in such organs as the liver, spleen and kidneys, CEUS is equally or more efficient than CECT. The advantages of CEUS are: non-invasiveness, high availability, short examination time, low cost expenses and good patient tolerance compared to contrast agents use in CECT and CEMRI. The appearance of UCAs decreased the gap dividing the diagnostic value of USG and CT/MRI and also allows the characterization of neoplastic lesions without the need of invasion biopsy and diagnostic laparatomy.