Cupressus macrocarpa and other Cupressus species
Monterey cypress
Evergreen tree up to 25m tall with reddish dark brown bark. Leaves are scale-like not protruding far from the branchlets. Flowers are unisex cones with mature cones being 2-4cm long.
C. lusitanica is being increasingly planted in the N. island as it is resistant to cypress canker. It is probably as toxic as C. macrocarpa.
Grown as a hedge and timber tree. Widespread and common in NZ.
Main toxin is isocupressic acid but a mixture of abietane-type acids has also been isolated. Abietane-type acids may cause depression, decreased appetite and death if sufficient quantities are present in the foliage. The exact mechanism of action of ICA is not known. Possibly related to binding of isocupressic acid to alpha2 adrenergic receptors or by interfering with oestrogen metabolites causing vasoconstriction of the uterine blood supply. Some pine trees also contain isocupressic acid.
Poisonings mainly recorded in cattle but poisoning of other livestock can occur.
Abortion and death in cattle is not uncommon in NZ. Sunken eyes, lethargy, loss of condition, severe depression. Abortion may occur 1-2 weeks post ingestion of large amounts of plant. Multiple abortions in herd often occur. Foetal membranes may be retained leading to a metritis.
Swelling of maternal cotyledons in aborted cows. Foetus may have leukomalacia of cerebral white matter.
From history, clinical signs, post mortem findings.
Remove retained membranes. Antihistamines may be beneficial if given early though there is no evidence to support this. Provide symptomatic care.
Reasonable if no complications i.e. metritis, toxaemia are involved.
Do not graze cattle in the last trimester where they can gain access to macrocarpa branches e.g. fallen branches from storm damage.
Conner H.E. The Poisonous Plants In New Zealand. 1992. GP Publications Ltd, Wellington
Parton K, Bruere A.N. and Chambers J.P. Veterinary Clinical Toxicology, 2nd ed. 2001. Veterinary Continuing Education Publication No. 208
Cooper M R, Johnson A W. Poisonous Plants and Fungi in Britan: Animals and Human Poisoning. Her Majesty’s Stationary Office. London. 1998
4 October, 2007
