Palicourea marcgravii is a shrub from the Rubiacea family, considered by many researchers to be the most important toxic plant causing sudden death in ruminants in Brazil. This plant is distributed throughout most of Brazil, has high palatability, high toxicity and an accumulative effect, as its leaves contain an extremely toxic poison, monofluoacetic acid-MFA. This toxin blocks the krebs cycle, causing an energy deficit. Its excretion can take up to five days after a single dose. If animals have access to plants, even in small quantities, ingesting their leaves, even in consecutive daily underdoses, can cause the death of the animal. The main clinical signs are predominantly cardiac, arrhythmias, but muscle tremors and even neurological, convulsions have also been observed.