Titian, Allegory of Prudence

The painting is customarily read as a depiction of the three ages of man and the three tenses: past, present and future, a token of the prudence that comes with the years.

But who, in that case, are the dog, the lion and the wolf meant to be in the allegory? According to one version, in this picture Titian portrayed himself in old age, his grown-up son and his young nephew; many scholars disagree, though what is there to disagree about? Look at Titian's self-portrait in old age in the Prado: the very image of the old man in the Allegory of Prudence.

The painting also bears an inscribed motto:
by learning from the mistakes of the past in the present, one may avoid harming one's future.

The painting is in the collection of the National Gallery in London; I saw it about four years ago at the Museo Poldi Pezzoli in Milan