Pregnancy termination in dogs with novel nonhormonal compounds.

Resorption of the products of fertilization was induced in bitches given (subcutaneously) single or multiple doses of the nonhormonal compounds L-10492 and L-10503 during the first half of gestation; also resorption or expulsion of the conceptus was induced when these compounds were given during the latter part of pregnancy. The smallest doses were required at a time immediately after implantation of the fertilized ova in the uterus. Effectiveness and appearance of side effects were dose-dependent. These consisted of decreased appetite, loss of body weight, and diarrhea (feces sometimes containing streaks of blood). Bitches which had aborted returned to estrus within normal intervals of time, exhibited normal mating behavior, and were fertile. They had normal deliveries and lactation, and the pups were normal. The mechanism of action does not involve effects on nidation and the compounds were not luteolytic, but probably involved the uteroplacental complex.