An extract of leech and earthworm for use in the prevention or treatment of thrombotic diseases, which is extracted from the leech Whitmania pigra Whitman, Hirudo nipponica Whitman or Whitmania acranulata Whitman and earthworm Pheretima aspergillum, Pheretima vulgaris Chen, Pheretima guillelmi or Pheretima peractimin , and which is characterized by a molecular weight of less than 5,800 DaltonUn extracto de sanguijuela y lombriz de tierra para usar en la prevención o tratamiento de enfermedades trombóticas, que se extrae de la sanguijuela Whitmania pigra Whitman, Hirudo nipponica Whitman o Whitmania acranulata Whitman y lombriz Pheretima aspergillum, Pheretima vulgaris Chen, Pheretima guillelmi o Pheretima pectinifera, y que se caracteriza por un peso molecular de menos de 5.800 Dalton
