Retrospective study to characterize post-obstructive diuresis in cats with urethral obstruction.

Urethral obstruction is a common medical emergency in cats. Frequency of post-obstruction diuresis in cats following resolution of urethral obstruction is unknown. The objective of this study was to document frequency and associated clinical features of post-obstruction diuresis in cats. The records of 32 cats undergoing 33 admissions to the Colorado State University Veterinary Hospital for urethral obstruction were reviewed. Signalment, admission blood values, fluid therapy, and urine output were recorded. Diuresis was defined as urine output greater than 2ml/kg/h. Post-obstructive diuresis occurred in 46% (13/28) of cats within the first 6h of treatment. Occurrence of post-obstructive diuresis was statistically more likely in cats with venous pH<7.35 on admission. Urine production following resolution of urethral obstruction should be monitored so that fluid therapy can be adjusted to the individual patient, as many cats will have a higher fluid requirement secondary to post-obstruction diuresis.