Objectives: To characterize the effect of acute unilateral and bilateral lesion of the pelvic and pudendal nerves, and nerves innervating the iliococcygeous and pubococcygeous muscles during sneezing in anaesthetized female cats, on intravesical pressure (IVP), urethral pressure (UPs) and external urethral sphincter (EUS) activity.
Materials and methods: In seven anaesthetized female cats UPs along the urethra (UPs1-4) and IVPs were recorded in the emptied bladder during sneezing before and after unilateral and then bilateral peripheral neural lesions. UPs were measured using microtip transducer catheters with UP4 positioned in the distal urethra where the EUS is located. Urine leakage was also noted, after urethral catheter removal and bladder filling.
Results: During sneezing, in intact cats, the magnitude of UP4 was larger than those of IVP and UPs1-3. The area under the curve of both anal sphincter and EUS electromyography was increased. There was no urine leakage. After unilateral neural lesions, the mean magnitude of response was similar all along the urethra and in the bladder. The distal UP response was significantly lower than that recorded in intact cats. In addition, there was urine leakage in six of the seven cats. Bilateral neural lesions caused permanent urine leakage and significant decreases in all the UP responses.
Conclusion: In female cats, during sneezing, neurally driven reflex contractions of EUS leading to an increase in distal UP contribute to active urethral closure mechanisms and ensure urinary continence.