Members of the Cupressus and Pinus species have been associated with malaise and abortion in late pregnancy in cattle for a number of years. The reports are world wide and often circumstantial but of too great a significance not to conclude that these species have a real toxicological significance.
Malaise and abortion in cattle associated with the ingestion of fallen or pruned macrocarpa has been reported frequently for many years in New Zealand. A similar clinical picture has been associated with the eating of Pinus radiata by cattle in late pregnancy, particularly where pines have been pruned.
Overseas countries have reported like situations, and the effects of eating the Ponderosa pine of North America are well documented. Also according to overseas reports many of the Cupressus species (Cypress) grown in parks, reserves and for shelter, can produce an identical poisoning to macrocarpa and pine. In 1994 isocupressic acid was identified as an abortifacient component of Ponderosa pine. Analysis of macrocarpa, radiata and other Cupressus spp. identified isocupressic acid in the foliage. A summary of trees associated with abortion in cattle or containing isocupressic acid is given in Table 66.
Cypress names are confusing, as many commercial and garden trees are hybrids. They are coniferous softwoods belonging to the closely related genera of Cupressus and Chamaecyparis. Cupressus (true cypresses) consists of some 19 species, of which C. macrocarpa (macrocarpa) from California and C. lusitanica (lusitanica), predominantly from Mexico, are commercial timber species in NZ. Chamaecyparis (false cypresses) consists of 7 species, the important timber species being C. lawsoniana (Lawson cypress) from western USA, C. nootkatensis (Nootka cypress) from Canada and Alaska and C. obtusa (Hinoki) from Japan. Hybrids between these have been cultivated. X Cupressocyparis leylandii (Leyland cypress, of which Castlewellan Gold is probably the commonest clone) is a cross between macrocarpa and Nootka cypress. X Cupressocyparis ovensii (Ovens cypress) is a cross between Lusitanica and Nootka cypress. Many other cypresses are grown in NZ parks and gardens.
Table 66 Cupressus and pine trees associated with abortion in cattle or known to contain isocupressic acid. The concentration is likely to be very variable.
| Common Name | Scientific Name | Concentration |
| Monterey Cypress or macrocarpa | Cupressus macrocarpa, Cupressus sempervirens | 0.89 - 1.24% (NZ) |
| Mexican cypress | Cupressus lusitanica | |
| Leyland cypress | Cupressus leylandii | 1.4% (NZ) |
| Lawson cypress | Chamaecyparis lawsoniana | |
| Golden cypress | X Cupressocyparis leylandii Castlewellan Gold | |
| Ovens cypress | X Cupressocyparis ovensii | |
| Radiata or Monterey pine | Pinus radiata | <0.1% (NZ) |
| Ponderosa pine | Pinus ponderosa | 1.7% (USA) |
| Lodgepole pine | Pinus contorta | |
| Common juniper | Juniperus communis |
Isocupressic acid is a labdane diterpene, and shares some structural similarities with steroids.
Approximately 100mg/kg isocupressic acid, or 2.7kg of dried ponderosa pine needles, twice daily caused abortion after 2 8 days in experimental cattle.
Isocupressic acid is thought to decrease blood flow in the caruncular arteries, possibly by interfering with catecholoestrogens' action on calcium channels.
Most abortions have been reported in the later stages of pregnancy. In some instance animals have had sudden access to macrocarpa or pine prunings or branches blown down in a storm. In others, particularly the losses from pine trees, cattle have been grazed continuously for some months with access to the pine needles, although in most cases tree lopping was being carried out during that period.
In cattle, severe depression has been recorded and this frequently precedes the abortion. In some cases following severe illness, cattle have died. In general the calves aborted have been in the advanced stages of development but too immature to survive. In nearly all cases the abortion is followed by retention of the foetal membranes and overseas reports involving the Ponderosa pine mention septic metritis and peritonitis as constant sequelae.
In some cases, the death of the cow has been so sudden at the time of abortion that it has been suggested that the pine needles contain a lethal toxic principle. This toxic principle is believed to be a mixture of abietane-type acids that cause depression, decreased appetite and death in cattle (Gardner et al. 1994).There are no distinctive lesions and no diagnostic tests which characterise these abortions. Cerebral leucomalacia has been reported in foetal brains in macrocarpa abortion. This may be of significance but further cases need to be investigated.
A history of access to cypress or pine prunings.
Infectious causes of abortion.
Other than careful nursing of sick cattle or cattle which have aborted, there is no special treatment. Earlier NZ experience reported value in the use of antihistamine drugs in early cases of the disease.
Gardner, D.R, Molyneux, R.J, James, L.F, Panter K.E. and Stegelmeier, B.L. (1994). Ponderosa pine needle-induced abortion in beef cattle: Identification of isocupressic acid as the principle active compound. Journal of Agriculture Food Chemistry. 42:756-761.
Hutton, J.B. (1996). (Macrocarpa) in Plant poisonings in New Zealand. Surveillance. 23(1):18-21.
Knowles, R.L. and Dewes, H.F. (1980). Pinus radiata implicated in abortion. N Z vet J. 28:103.
MacDonald, J. (1956). Macrocarpa poisoning. N Z vet J. 4:30.
Parton, K.H, Gardner, D. and Williamson, N.B. (1996). Isocupressic acid, an abortifacient component of Cupressus macrocarpa. N Z vet J. 44:109-111.
Stevenson, A.H, James, L.F. and Call, J.W. (1972). Pine needle (Pinus ponderosa) induced abortion in range cattle. Cornell Vet. 62:519-524.
Surveillance (1974) 1(3): 9 Macrocarpa and pine needles in bovine abortion
Surveillance (1974) 1(3):13 Macrocarpa abortion
Surveillance (1974) 1(4):7-8 Macrocarpa and abortion
Surveillance (1975) 2(3):20 Macrocarpa abortion
Surveillance (1998) 25(4):13 Macrocarpa abortion in cattle
Surveillance (1999) 26(2):17 Leyland cypress (Cupressus leylandii) abortion in cattle