Technique, anatomy and changes associated with disease

Practical relevance: Ultrasonography is an important tool for the detection of kidney disorders, which are among the most common health problems suffered by cats. It is more accurate than radiography for this purpose and is considered to be the reference modality for imaging the feline kidney, providing excellent visualisation of renal size, shape and internal architecture. Compared with more advanced imaging modalities, such as computed tomography or magnetic resonance imaging, ultrasonography is more accessible, less expensive, does not require general anaesthesia and allows real-time procedures to be performed. Clinical challenges: On ultrasound examination, focal or multifocal disorders may be readily identified, but diffuse changes are more challenging. B-mode ultrasonography is of limited use for differentiating between benign and malignant focal lesions. However, based on the presence and pattern of vascularity as an indicator of malignancy, contrast-enhanced ultrasonography allows distinction between benign and malignant focal renal lesions. Audience: This review provides a framework for the ultrasonographic approach to feline renal and perirenal disorders for the general practitioner. Evidence base: Drawing on current literature relating to ultrasonographic examination of feline kidneys, the aim is to summarise ultrasonographic technique, anatomy and changes associated with renal and perirenal diseases.