Bovine retained placenta: effects of collagenase and hyaluronidase on detachment of placenta.

A significant percentage of cows (11%) fail to release the placenta within 12 h postpartum. Failure of collagen breakdown seems to be related to the retention of placentas. Sections of placentomes incubated with bacterial collagenase caused an increase in placentome proteolysis (6.6-fold) and placentome collagenolysis (94-fold) within 4 h in a dose-related fashion (r = 0.94). Injections of collagenase (825 U/cc) into the placentomes, via umbilical vessels, decreased the cotyledon-caruncle binding force (determined by manometry) to 30 +/- 5 mm Hg from 97 +/- 2 mm Hg, and increased proteolysis by 42% within 8 h (r = -0.95). Hyaluronidase at various concentrations (400-8 250 U/cc) and at various incubation times (up to 8 h) was not effective. Hyaluronidase (825 U/cc) and collagenase (825 U/cc) were not synergistic in loosening cotyledon-caruncle attachment. A single 15-min collagenase pulse, given prior to perfusion with collagenase-free blood, was as effective in loosening cotyledon attachment as was a sustained 2-h perfusion of blood with collagenase added. It was concluded that collagenase caused collagenolysis and loosening of cotyledon from caruncle, but collagenolysis and cotyledon-caruncle separation were not facilitated by the presence of hyaluronidase.