Is Ngaio Tree Poisonous? – Hepatotoxic Risk for Pets and Livestock

Ngaio tree is toxic to animals, with documented liver damage in livestock and potential risk to dogs. The plant contains ngaione, a furanosesquiterpene found primarily in the leaves, which is hepatotoxic and can cause serious liver injury. It is native to New Zealand and grown as an ornamental or windbreak tree in temperate coastal regions. If you have animals that graze or browse near ngaio trees, treat access to the foliage as a genuine hazard.

What Is the Ngaio Tree?

Ngaio is the common name for Myoporum laetum, a fast-growing evergreen tree or large shrub native to New Zealand. The name “ngaio” comes from the Maori language. The tree has shiny, dark green leaves, small white flowers with purple spots, and small purple-red berries. It is widely planted in coastal gardens, used as a hedge or windbreak, and has naturalized in parts of the United States, Australia, and South Africa.

The tree is sometimes encountered in suburban gardens or along roadsides in areas with mild climates. Its tolerance for wind and salt spray makes it a common choice for coastal planting.

Which Parts Are Toxic?

The leaves are the primary source of toxicity. They contain ngaione, a furanosesquiterpene that accounts for the majority of the tree’s essential oil content. Ngaione is hepatotoxic, meaning it directly damages liver tissue, causing periportal hepatic necrosis.

The flowers and berries are also part of the plant and should not be considered safe, though the leaves are the most documented source of poisoning. Young leaves and wilted or fallen leaves can retain the toxic compound.

Symptoms of Ngaio Tree Poisoning

Toxicity is best documented in livestock, particularly cattle and sheep, where poisoning has occurred through grazing on ngaio foliage.

Dogs and cats: Ngaione-induced liver damage is the primary concern. Symptoms include loss of appetite, lethargy, vomiting, jaundice (yellowing of the whites of the eyes or gums), and abdominal discomfort. Photosensitization, a condition in which damaged skin becomes hypersensitive to sunlight and develops lesions, has also been documented in affected animals.

Livestock (cattle and sheep): Well-documented poisoning with liver failure. Affected animals show apathy, eye discharge, abdominal pain, constipation, jaundice, and photosensitization. The liver shows severe enlargement and discoloration, with periportal necrosis on pathological examination.

Humans and children: Direct poisoning from casual contact is unlikely. The plant is not commonly consumed by people, and there are no well-documented cases of serious human poisoning through ordinary garden contact. As with any plant containing bioactive compounds, eating any part of it is inadvisable, particularly for young children who may ingest leaves or berries.

What to Do If an Animal Ingests Ngaio

1. Remove the animal from access to the plant immediately.
2. Call your vet without delay. Liver damage may not produce obvious symptoms until it has progressed.
3. Call poison control at 1-800-222-1222 (US) if a person has ingested any part of the plant.
4. Describe the plant clearly and report how much was consumed and when.
5. If your livestock have grazed on ngaio, contact a farm veterinarian who can assess liver function through blood tests.

Early intervention matters with hepatotoxic poisoning because liver damage is cumulative. Do not wait for jaundice to appear before seeking help.

Safe Handling and Risk Reduction

• Do not allow horses, cattle, sheep, or goats to browse ngaio foliage.
• Fence off ngaio trees in paddocks or grazing areas.
• Collect and dispose of fallen leaves and branches that land within reach of livestock or dogs.
• Wear gloves when pruning and wash hands afterward.
• If you are planting a windbreak or hedge in an area with grazing animals, choose a non-toxic alternative species.

Frequently Asked Questions

Is ngaio toxic to all animals or only livestock? Toxicity is most extensively documented in cattle and sheep, where grazing incidents have been studied. Dogs are also at risk from hepatotoxic compounds. The mechanism of liver damage from ngaione is not species-specific, so caution is warranted for all animals that might eat the foliage.

Are the berries safe to eat? The berries of ngaio tree should not be eaten. The plant’s hepatotoxic compounds are concentrated in the leaves, but no part of the plant has been established as safe for consumption.

Can ngaio tree harm humans through skin contact? Routine garden contact is unlikely to cause serious harm to humans. The primary route of toxicity is ingestion. Wash hands after prolonged handling of leaves or sap.

How does photosensitization from ngaio work? Liver damage from ngaione impairs the organ’s ability to process certain pigments derived from plants. These pigments accumulate in the bloodstream and reach the skin, where exposure to ultraviolet light causes inflammatory reactions and skin lesions. This is secondary photosensitization, a recognized consequence of hepatotoxic plant poisoning.

Is ngaio tree grown in North America? Yes. It has been planted as an ornamental and windbreak in coastal areas of California and other warm, maritime regions. Check with your local extension service or native plant authority if you are unsure whether a tree in your garden is ngaio.