What does Mark Strand want to show us in his poem "Eating Poetry"?

The most likely message that Mark Strand is trying to communicate in his poem is the joyous experience that reading really good poetry often can be for people.  When you read a really good poem, absorb it and take it into your mind and heart, it sometimes almost feels like you are transformed; Strand represents this with a literal picture of "eating" poetry, which is more likely a symbol for reading a poem.  Poets, writers and readers have tried to describe the physical experience of reading a really good poem; Emily Dickinson, a famous American author, said that reading a good poem felt like the top of her head had been taken off.  Others describe it as a ray of light penetrating their hearts, being filled with revelation, and like a rush of wind blowing through their minds.  So, reading a really good poem definitely has a physical impact; anytime you recognize beauty, revelation or profundity, it awes, it takes your breath away, it moves you, sometimes to goosebumps or tears.

Mark Strand took this idea of reading good poetry to a rather unique angle--he compared it to feeling like a joyful, exuberant, reckless, ridiculous dog.  Dogs, when happy and excited, jump about, pant, wriggle, bark, run everywhere, and seem to be so overwhelmed with their glee and joy of living that they can't even contain themselves.  Well, perhaps that is what Strand feels like when he reads a good poem--overwhelmed with joy and glee, and wanting to jump around like a silly dog to release the happiness he feels.

Strand is showing us the complete joy that abandonment to a good poem can be; he takes a rather unusual and almost disturbing and literal route to do it, but, conveys that sense of joy that poetry can bring to someone.