Disruption of pregnancy in rabbits serving as hosts for feeding ticks

The effect of tick infestation on reproductive success of mammals was studied by using rabbits bred after they had served as hosts for Dermacentor variabilis . Mating success, pregnancy incidence, litter size and neonatal viability were reduced in tick-exposed rabbits, and the proportional number of abnormalities found in preimplantation-stage embryos was much higher than in unexposed controls. Fecundity was restored by prolonging the interval between tick exposure and breeding or by treatment with an acaricide.