The speaker is crouched beside a gravestone, struggling to read or find words for someone who has died. Small clues suggest this is a dog: the "upraised paw," the "toys and bones," the fear of fireworks. The speaker admits he couldn't fix death the way you might pull a thorn from a hurt paw, and that helplessness sits at the heart of the poem.
His grief comes out in wishes. He wishes the dog were next to him, enjoying the butterflies, the eucalyptus trees and the sun, instead of lying beneath his shadow. That small image is striking, since even his own presence seems to darken the place where the dog rests.
The fireworks of Independence Day bring the most painful thought. He hopes they didn't scare the dog, then pictures it alone with its toys, and wishes he could have held and soothed it. The mood is quiet, tender and full of regret. The poem never raises its voice, which makes the guilt and love feel all the more real.