In temperate and sub-tropical climates white oleander is a common large ornamental shrub. Oleander is a very toxic plant and all parts of the plant must be kept away from horses. Horses that consume as little as one ounce of leaves can be poisoned.

Oleander toxicity is a known cause of sudden death in horses. Horses eating more than several ounces of oleander leaves may simply be found dead within 12 hours of ingestion.

If found before death, affected horses are likely to show signs of colic and diarrhea. Most will be in shock and have very high irregular heart rates, rapid or labored breathing, weakness and wobbliness, or can also be down and seemingly unable to rise. Convulsions are common preceding death.

DIAGNOSIS is by clinical signs in a horse that has had exposure to Oleander. Post-mortem, the diagnosis can be made through finding the plant in the stomach.

TREATMENT: There is no specific treatment for counteracting the effects of the toxins. Treatment is limited to supportive nursing care and symptomatic treatment.