Professor Elena Parma has kindly confirmed the attribution to Perino on the basis of a photograph.
Similar dragons can be found in Perino's studies for a Saint George and the Dragon in the Szépmüvészeti Museum, Budapest, and the Nationalmuseum, Stockholm (E. Parma et al., Perino del Vaga, tra Raffaello e Michelangelo, exhib. cat., Mantua, Palazzo Te, 2001, no. 69 and p. 176) and a drawing of Saint Paul defeating the serpent, for the cope of Pope Paul III, in the British Museum, London (E. Parma, op. cit., no. 149).
The drawing will be included in an article written by Professor Parma for the Atti of the Perino Symposium held in Genoa in 2001.