Per Ernest's message with thanks to him:

Boatswain
At the death of 'Boatswain', the Newfoundland who was the trusted friend of Lord Byron, the famed English poet has a monument erected on his grave at Newstead abbey. Then he wrote the following poem, which was etched on one side of the octagonal shaft:

When some proud son of man returns to earth,
Unknown to glory, but upheld by birth,
The sculptor's art exhausts the pomp of woe,
And storied urns record who rests below;
When all is done, upon the tomb is seen,
Not what he was, but what he should have been.
But the poor dog, in life the firmest friend,
The first to welcome, the foremost to defend,
Whose honest heart is still his master's own,
Who labors, lives, fights, breathes for him alone,
Unhonored falls, unnoticed all his worth,
Denied in heaven the soul he held on earth.
While man, vain insect, hopes to be forgiven,
And claims himself a sole, exclusive heaven.
Ye! Who behold, perchance, this simple urn,
Pass on; it honours none you wish to mourn.
To mark a friend's remains these stones rise,
I have never known but one - and here he lies.