Caixeta, a wood common to South America, in the genus Simarouba and in the family Simaroubaceae, was reported to cause blisters in the mouth in 1998. Then in 2000, 26 of 28 horses stabled on imported shavings of this wood developed blisters and ulcers around the mouth, nose, lips, and anus within 48 hours of exposure. This article is about the research into this plant's toxicity, clinical signs, treatment, and prognosis of horses that develop toxicity.

Simaruba is a medium sized to large tree that grows up to 15 to 25 meters in height with a trunk 50-80 cm in diameter. It produces bright green leaves 20 to 50 cm in length and with small red fruits. It is indigenous to the Amazon Rainforest and other tropical areas in Mexico, Cuba, Haiti, Jamaica and Central America. The wood and shavings have been exported for use with livestock.