The Martyrdom and Transport of the Decapitated Body of Saint Christopher painted by Andrea Mantegna in the Ovetari chapel of the church of the Eremitani in the mid XV century. The church was badly damaged by bombing in 1944 with dramatic consequences for the frescoes painted by the Renaissance master.
On the left it looks (almost entirely scraped off) like there is a large animal eye in a large animal’s head, on the outline of a man’s body with his hands tied. Can anyone else see that? It would match the idea of St. Christopher as cynocephali!