Castor bean (Ricinus communis) in Pets

Chewed castor beans release ricin, and one or two seeds can be fatal to a dog. Learn why signs are delayed, why castor meal fertiliser matters and what to do now.

What It Is

The castor oil plant produces mottled, bean-like seeds containing ricin, a protein that stops cells from making proteins and kills them. The seed coat is hard, so a seed swallowed whole may pass through, but chewed seeds release ricin. Commercial castor oil has had the ricin removed.

Where Pets Come Across It

Ornamental castor oil plants with large star-shaped reddish leaves in gardens and parks, decorative seed jewellery, and organic fertilisers made from castor seed cake (castor meal) used on lawns and flower beds.

Which Animals Are Affected

Dogs most often, because they chew seeds and eat fertiliser pellets. Horses, livestock, birds and cats can also be poisoned.

Published Toxic Dose

No mg/kg figure for ricin exposure is meaningful for owners, because ricin content varies and depends on chewing. Pet Poison Helpline states that chewing and swallowing just 1–2 seeds can lead to severe gastrointestinal signs, organ failure and death. So the calculator does not grade the dose; seeds chewed is the number to report.

Signs and How Soon They Appear

Signs are often delayed by several hours to a day or more: vomiting, severe and sometimes bloody diarrhoea, abdominal pain, drooling, weakness and fever, followed by dehydration, low blood pressure and liver or kidney damage.

What to Do Right Now

Call your vet or a poison line straight away, even if your pet seems fine; the delay before signs is when care is most effective. Bring a seed or the fertiliser bag. Do not induce vomiting at home.

Spotting castor plants and castor fertiliser

The castor oil plant is a fast-growing annual or shrub with large, glossy, palm-shaped leaves, often bronze or deep red in ornamental varieties, and spiny seed capsules that split to release shiny, mottled seeds about 1 cm long. It is popular in tropical-style summer bedding. Organic lawn and garden fertilisers sometimes include castor seed meal; labels may say 'castor meal' or 'castor pomace'. Dogs find these fertilisers palatable, and poisoning reports in dogs have followed eating them. Check the ingredients of any organic fertiliser before use, store bags securely, and water products in thoroughly. If you grow castor plants, remove seed capsules before they ripen, and do not let children make jewellery from the seeds.

Frequently Asked Questions

Sources and References

• Pet Poison Helpline: Castor Bean
• ASPCA: Castor Bean Plant

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