EQUINE RETAINED PLACENTA - TECHNIQUE FOR AND TOLERANCE TO UMBILICAL ARTERY INJECTIONS OF COLLAGENASE

Under laboratory conditions and in clinical experiments, bacterial col lagenase has proven to be effective in hydrolyzing placenta and detach ing cotyledon from caruncle in the bovine species. Laboratory studies in which placental samples were incubated with collagenase have also d emonstrated that collagenase is 3.7 times more effective in hydrolyzin g equine placenta than bovine placenta. This led to the hypothesis tha t collagenase may be a potential treatment for mares with retained pla centa. However, that collagenase may hydrolyze the uterine wall and pe rforate the uterus was a concern. It was the purpose of this study thu s to determine any adverse effects of collagenase on the equine uterus and to develop a method for intraplacental injection of collagenase. Three normally expelled intact placentas from Arabian mares, 10 cyclic mixed-breed mares, and 4 mares of various breeds with retained placen ta were used. Fluoroscein dye and latex were used to study the placent al vasculature and to determine a suitable dose of collagenase; placen tas were hydrolyzed by collagenase solution in vitro. Bacterial collag enase solution (40,000 units, 200 ml) was infused into the uterine lum en of each cyclic mare. Uterine biopsies were obtained from the mares before collagenase infusion and again at 16 h and 26 d after infusion. In the mares with retained placenta, each placenta was infused via it s umbilical cord vessels with 200,000 units of bacterial collagenase i n 1 L of saline. Results showed that none of the uteri from cyclic mar es were damaged by collagenase treatment. During a 4-wk period of moni toring (including endoscopy) mares with retained placenta did not show any abnormalities. Retained placentas were expelled in less than 6 h after collagenase treatment. It was concluded that intraplacental inje ctions of collagenase are a safe and potentially effective treatment f or retained placenta in mares. (C) 1998 by Elsevier Science Inc.