She must have been kicked unseen or brushed by a car.
Too young to know much, she was beginning to learn
To use the newspapers spread on the kitchen floor
And to win, wetting there, the words, "Good dog! Good dog!"
The dog seems to be young due to the fact that this line says, “She must have been kicked unseen or bruised by a car” which can tell the reader that the dog was not old.  If the dog was old, John Updike would have just said something that implicated that she was old and not that is looks like something or someone hurt the dog and that is why the dog is dying. The line is then backed up with the next line that states, “Too young to know much,” which means the dog was young.  The first line is giving the reader some what of a relief so they don’t read the whole poem wondering the whole time what happened to the dog and why it is dying.
Dogs Death