Evaluation of a modified surgical technique to correct urine pooling in cows.

Various surgical techniques to correct urovagina in cows describe creating a mucosal extension from the urethral orifice to the labia; however, a fistula often forms in the mucosal extension. The objective of the present study was to determine if the incidence of fistula formation could be decreased by covering transposed submucosal tissue on the dorsal aspect of the urethral extension with a mucosal graft. Cows in both the control group (19) and the experimental group (19) received a modified McKinnon technique of urethral extension; cows in the experimental group also had a sheet of mucosa, obtained from the dorsal aspect of the vestibule, grafted to submucosa exposed during creation of the urethral extension. During histological examination of the biopsy of the graft and its recipient site (harvested 1 week after surgery), neither inosculation nor revascularization of the graft was evident in any sample. Fourteen of 19 (74%) cows in the control group and 10 of 19 (53%) cows in the experimental group developed a fistula in the extension (P=0.18). We concluded that application of a mucosal graft to the subcutaneous tissue exposed to the vestibule using the McKinnon technique of creating a urethral extension was of little or no benefit in preventing the formation of a fistula in the extension. Furthermore, during evaluation of the extensions, digital palpation alone was often insufficient for detection of a fistula.