Results of retrograde urethrography in cats with idiopathic, nonobstructive lower urinary tract disease and their association with pathogenesis: 53 cases (1993-1995).

To describe results of retrograde urethrography in cats with idiopathic, nonobstructive lower urinary tract disease (LUTD), to review the normal anatomy of the feline urethra, and to relate anatomy observed radiographically to the pathogenesis and diagnosis of LUTD in cats. Retrospective case series and anatomic study. 53 cats with signs of nonobstructive LUTD for which an underlying cause could not be determined. Results for these cats were compared with those for 6 healthy female cats undergoing urethrocystoscopy for another study and 6 male cats without a history of LUTD undergoing necropsy examination. Medical records, results of positive-contrast retrograde urethrography (cats with idiopathic, nonobstructive LUTD) and urethrocystoscopy (healthy female cats), and necropsy findings (healthy male cats) were reviewed. Abnormalities were not detected during urethrocystoscopy, dissection, or urethrography. Previously, the urethra in male cats has been described simply as a long tube that tapers caudally, and the only structures consistently differentiated by radiography have been pelvic and penile parts. In this study, the seminal colliculus, isthmus of the urethra, preprostatic part of the urethra, and urethral crest were consistently observed in male cats in addition to pelvic and penile parts. The urethral crest also was observed in the comparatively simple female urethra. During retrograde urethrography in cats, prior distention of the bladder with positive-contrast medium may obscure radiographic signs associated with normal anatomic structures. Knowledge of urethral anatomy and radiographic signs associated with idiopathic, nonobstructive LUTD in cats should improve understanding of the pathogenesis and diagnosis of this disease.