I found the lyrics to this song in J.E. Carpenter's collection Later Lyrics (1878, p. 10), when I was searching for songs with a codgeresque theme. It was written by W.T. Wrighton, who largely wrote or set sentimental songs, judging from other compositions I've located. But I presume from the text that it was written more for the music hall than the parlor. I've tried to give it a "period" tune which is light-hearted, if not jovial, though in period I may be off by a decade or so.

For a score and MIDI, you can pop the ABC transcription into the folkinfo.org ABC Converter; a MIDI link should also appear on this page anon.

You can find more of my settings and such through this thread: Artful Codger


THERE IS LIFE IN THE OLD DOG YET!
   W.T. Wrighton, by 1878

They call me "old fellow" and only because
   My beard has some patches of grey;
I am well on the road I admit, but you'll own
   We must all of us travel that way ;
I often look back to the scenes of my youth,
   But not with a sigh of regret,
And to cheer me along, I can sing an old song,
   Yes ! there's life in the old dog yet.

If I am an old fellow, why so let it be,
   'Tis the maxim of age to speak truth,
And the reason I'm happy and hearty is this,
   I was merry and wise in my youth ;
I have many old friends, and I never lost one
   That kind Heaven has spared, since we met,
And to cheer them along, I can sing them a song,
   Yes! there's life in the old dog yet.

My maxim has always been live and let live,
   And life to enjoy by the way,
If I've saved a few pounds, I have spent many more,
   What I owe I can manage to pay;
I can still take my glass, I've an eye for a lass,
   All my cares I contrive to forget,
While to cheer me along, I've my friends and my song,
   Yes ! there's life in the old dog yet.


Source: Later Lyrics (p. 10), ed. Joseph Edwards Carpenter, London, 1878. Originally published by R. Cocks and Co.
First line index (with authors): p. 265
http://books.google.com/books?id=lXQCAAAAQAAJ&pg=PA10


ABC:

X:1
T:Life in the Old Dog Yet
C:Text by W.T. Wrighton, by 1878
C:Music by Robert Wahl, 2012
%%writefields S
S:Text: Later Lyrics (p. 10), ed. Joseph Edwards Carpenter, London, 1878.
%%printparts 0
P:AAA
%%MIDI program 1 0   % Acoustic grand piano
%%MIDI gchord fzczczfzczcz
M:6/8
L:1/8
Q:3/8=72
K:Eb
P:A
"^(A)"(B/A/) | "Eb"G>^FG "^(B2)"c<BG | "C7"=E>^DE A2 G/C/ | "F"FGF E>FE | "F7"C3z^CC |
w: They* call me "old fel-low" and on-ly be-cause* My beard has some patch-es of grey; I am
"Bb7"D>FD (C<C)(E/E/) | D>FD B,>CD | "Eb"EDE "Cm"G<cG | "Bb7" B3 zBA |
w: well on the road* I ad-mit, but you'll own We must all of us trav-el that way;* I
"Eb"G>^FG B>BB | "C7"=E^DE G2C | "Fm"F>=EF AGA | c3 "B7"_c2c |
w: of-ten look back to the scenes of my youth, But not with a sigh of re-gret, And to
"Eb"BGF E=D_D | "Fm"C/F/ A2 "D7"cHLd3/c/ | "Eb/Bb"BzB,/B,/ "Bb7"G2F |
w: cheer me a-long, I can sing an old song, Yes, there's life in the old dog
"Eb"B3 "Ab6"G2F | "Eb/Bb"B,2=A,/B,/ "Bb7"G2B, | "Eb"E3 z2 ||
w: yet. Yes, there's life in the old dog yet.
%
%%vskip .25in
%%center Copyright \251 2012 by Robert Wahl. All rights reserved.
%%abc-copyright Copyright \251 2012 by Robert Wahl. All rights reserved.
%%leftmargin 2.5in
%%begintext

2. If I am an old fellow, why so let it be,
    'Tis the maxim of age to speak truth,
And the reason I'm happy and hearty is this,
    I was merry and wise in my youth;
I have many old friends, and I never lost one
    That kind Heaven has spared, since we met,
And to cheer them along, I can sing them a song,
    Yes! there's life in the old dog yet.

3. My maxim has always been live and let live,
    And life to enjoy by the way,
If I've saved a few pounds, I have spent many more,
    What I owe I can manage to pay;
I can still take my glass, I've an eye for a lass,
    All my cares I contrive to forget,
While to cheer me along, I've my friends and my song,
    Yes! there's life in the old dog yet.
%%endtext
%%vskip .25in
%%leftmargin 1.25in