Slopes, valley and mesas, generally on south-facing slopes
Cattle, bison, sheep
The toxic principle has been identified as isocupressic acid, a diterpene acid. Other diterpine acids, and lignols isolated from pine needles may also be involved in causing abortion. The toxins cause a marked decrease in blood flow to the uterus that results in death of the fetus
Cattle appear to eat the pine needles when stressed or when normal forage is scarce such as during winter snow storms. Green or dried needles, and the bark are toxic.
Sheep, goats and bison are suceptible to isocupressic acid poisoning.
Other species of Pinus that contain isocupressic acid with the potential to cause abortion include lodgepole pine, Jeffrey pine, Rocky Mountain juniper (Juniperus scopulorum), common juniper, and Monterey cyprus (Cupressus macrocarpa).
Tree 15-45 m. tall, often broad and round-topped with thick, brown bark which separates into cinnamon-brown scales or flakes. Needles are 8-25 cm long in 3's or 2's, yellowish green in color. The cones are subsessile, ovoid in shape and 7-15 cm long. The thickened scales have a short, recurved prickle on the apex.
Treatment for retained fetal membranes may be necessary.
Renal failure due to abietane resin acids in new growth pine needles occurs in cattle.
Abortion. Cattle consuming pine needles in the last trimester of pregnancy will abort anywhere up to 2 weeks later. Cows develop edematous swelling of the vulva and udder prior to abortion. The fetus is usually autolyzed indicating it has been dead in utero for several days prior to abortion. The incidence of retained placentas following abortion is high. Sheep may have a high incidence of dead lambs after eating pine needles. Agalactia and retained fetal membranes are common in cows that abort.
Late term abortions and evidence of pine needles being consumed.
Other species of pine tree, spruces, and firs have not been incriminated in causing abortions. Some cypress, and Pinus radiata contain isocupressic acid and therefore may cause abortion. The red pine (P. resinosa) has not been associated with abortion in cattle.
Bald cypress (Taxodium distichum)is not know to be toxic.