Pieter Gaal came from a family of painters from Zeeland and was a pupil of Jacob Perkois (1756-1804) and Hendrik Willem Schweickhardt (1746-1997). After travelling to England, France (he studied at the Académie des Beaux-Arts de l'Institut de France), Italy, France, Swiss and Germany he settled in Middelburg and spent the summers in his countryhouse in Oost-Souburg. His main interest were lanscapes with cattle and travellers. Gaal also worked after 17th century Old Masters like Jan Both, Nicolaes Berchem and Anthony van Dyck.
A comparable drawing by H.W. Schweickhardt of a reclining swine (Truie couchée) in the collection Masson.
 Frits Lugt, Inventaire général des dessins des écoles du Nord: École Nationale Supérieure des Beaux-Arts, Paris. Henri laurens, paris, 1950. Vol I, no. 591, p. 612-613.