The library of the Societat Castellonenca de Cultura (Castelló de la Plana) keeps a Catalan manuscript on menescalia (veterinary medicine) virtually unknown to the specialists. Here we provide a diplomatic description, a presentation of its content, and particularly a first linguistic analysis. Our study allows us to locate its elaboration in the mid-14th century within the area of Morella, and to attribute it to a paraire or to a merchant. The manuscript is currently in the process of being edited.