Which plant is associated with hemorrhagic toxicosis due to the anticoagulant agent dicoumarol?

• A. Sweetclover (Melilotus)
• B. Legume hay
• C. Nitrate-containing plants
• D. Primary photosensitization plants

Answer: (A)

Dicoumarol is produced by mold in spoiled sweet clover hay, and this compound acts as a vitamin K antagonist. When animals ingest moldy Melilotus, dicoumarol interferes with the gamma-carboxylation of clotting factors II, VII, IX, and X, rendering them nonfunctional. The result is a deficiency of functioning clotting factors and a tendency to spontaneous hemorrhage, which is why this plant is classically linked to hemorrhagic toxicosis.

Clinical signs reflect defective blood clotting and can include mucosal bleeding, epistaxis, bruising, and other hemorrhages after a few days to weeks of exposure. Treatment centers on replenishing vitamin K1 and, if needed, providing blood products or plasma to control active bleeding, along with removing the source. Prevention hinges on avoiding moldy or poorly cured sweet clover hay and storing forage properly to prevent mold growth.

Other plant categories listed do not specifically relate to dicoumarol-induced anticoagulation: nitrate-containing plants cause nitrate poisoning; primary photosensitization plants cause photosensitivity; and legume hay per se is not associated with this hemorrhagic syndrome.