Two Unique Cases of Ponderosa Pine Needle-Induced Abortions

Ponderosa pine (Pinus ponderosa) needles can induce abortions in cows when consumed during the last trimester of pregnancy. Traditionally pine needle-induced abortions occur in areas where cattle are forced into a stand of ponderosa pine trees to seek shelter and feed during a winter storm that is either very cold, has heavy snow or high winds. However, here we report two incidences of pine needle-induced abortions in cattle that were unique. In one case, there was no weather-related event that forced the cattle into the stand of pine trees, rather the cattle went into the pine trees seeking the new growth of grasses near the pine trees. In the second incident, the abortions occurred in an area with no previous history of pine needle-induced abortions, which may be due to the low concentration of abortifacient compounds in the needles from that area. However, in both cases, the resultant abortions, as well as the effects on the cows and calves, were consistent with pine needle-induced abortions. All of the cattle that aborted had retained placentas and all of the calves that were tested had high concentrations of tetrahydroagathic acid, a metabolite of isocupressic acid, the abortifacient compound in ponderosa pine needles. These two cases highlight the fact that when cows are allowed to graze in areas with ponderosa pine needles during the last trimester of gestation there is always a risk for the cattle to consume enough pine needles for abortions to occur.