Urinary system diseases are commonly observed in cats and dogs. In the etiology of urinary bladder diseases; traumatic factors, housing multiple animals in confined spaces, dry food-based diets, insufficient water intake, and obesity are included. In clinical examinations, patients usually present with signs such as dysuria, pollakiuria, hematuria, stranguria, crystalluria, and pain in the caudal abdomen. Since anamnesis and urinalysis alone are not sufficient for the diagnosis of urinary system diseases, radiography and ultrasonography are utilized. Ultrasonography is a reliable method that can be applied painlessly, non-invasively, without the need for sedation, without using contrast agents, and without exposure to radiation. This method allows for the evaluation of bladder size, shape, wall structure, echogenicity, and contents. Additionally, it increases the safety of interventional procedures such as cystocentesis and biopsy, and enables the determination of the size, number, location, and shape of radiolucent or radiopaque uroliths. In ultrasonographic examinations, cystitis, bladder inversion, neoplasms, blood clots, trauma, and foreign bodies are also evaluated. Ultrasonography stands out as a reliable and practical method for the diagnosis of urinary bladder diseases in cats and dogs compared to other imaging modalities.