Effective evaluation of urethral function in incontinent female dogs is accomplished by urethral pressure profilometry (UPP), which measures urethral pressure from the bladder neck to the external urethral orifice. Restraint via sedation is usually required, however; and many anesthetic agents decrease urethral pressure, making it difficult to evaluate differences between normal and abnormal findings. Propofol has been reported to have the least effect on UPP in female dogs but also has adverse effects, including being difficult to control, that make it less than desirable for single use. Newer inhalant anesthetics, such as sevoflurane, have not been evaluated for their suppressive effect on UPP but are easier to control and less expensive and may provide a more reliable and convenient method for restraining patients during UPP. In this study, anesthesia with sevoflurane was compared with propofol and no anesthesia (awake dogs) in 10 clinically normal females. Drug concentrations were systematically varied for each agent to determine the effect of anesthetic depth on UPP and contrasted with recordings in the awake dogs.

Urethral pressure of awake dogs did not differ significantly from that of dogs anesthetized with propofol at all infusion rates or with sevoflurane at 1.5% and 2.0% end-tidal concentration. Functional urethral area in awake dogs was significantly higher than in anesthetized dogs, and functional area in dogs anesthetized with sevoflurane at 3.0% end-tidal concentration was significantly lower than that in dogs anesthetized with propofol. Individual differences also were observed.

Sevoflurane is an acceptable alternative to propofol for UPP. Use of either of these agents at appropriate administration rates should reliably distinguish normal from abnormal functional areas as well as maximal urethral closure pressure. Titration of anesthetic depth is a critical component.

COMMENTARY: Although UPP is seldom done in practice settings, this procedure can provide important information for accurate prognosis and appropriate management in dogs with ectopic ureters. This paper suggests that anesthesia with either propofol or sevoflurane is reasonable for this procedure because of the minimal effect on the maximal urethral closure pressure and functional urethral length.

Comparison of the effect of propofol and sevoflurane on the urethral pressure profile in healthy female dogs. Byron JK, March PA, DiBartola SP, et al. AM J VET RES 64:1288-1292, 2003.