Western Juniper-Induced Abortions in Beef Cattle

It has been known for many years that ponderosa pine needles can induce late-term abortions in cattle. Labdane acids including isocupressic acid (ICA) and agathic acid are responsible for initiating abortions. Recent research demonstrated that a number of trees including many species of pine, juniper, and cedar contain either isocupressic acid or agathic acid at concentrations sufficient to be a risk for causing abortions in late-term cattle. The objective of this study was to determine if the bark from western juniper (Juniperus occidentalis) will induce late-term abortions in cattle. Pregnant cows were dosed starting on day 250 of gestation with 2.3 kg of ground plant material twice daily for 10 days or until abortions occurred. Western juniper bark used in this study contained approximately 0.7% labdane acids, on a dry weight basis, including isocupressic acid (0.025%), agathic acid (0.43%), imbricatoloic acid (0.15%), and dihydroagathic acid (0.05%). Two cows aborted 4-5 days after the start of the treatment. Both cows had retained placental membranes. The remaining 4 cows calved at full term (26-31 days after the start of treatment) and had no retained placental membranes. Results from this study indicated that western juniper trees contain compounds known to be abortifacient in cattle and that consumption of large amounts of bark in the third trimester of gestation may induce abortions. Although the risk of abortion from eating western juniper bark appears to be less than that from eating ponderosa pine needles, livestock producers should be aware of this potential.