If it's a .45 Long Colt then there are loadings that will be fine for deer, but this cartridge is also popular with the Cowboy Action shooters and some loadings aren't very powerful...
I would guess that the 3-4 most popular revolver cartridges for deer hunting are the .44 Mag, the .41 Remington Mag, the .45 Long Colt and the .357 Mag...
Finally...My Glock 23 in .40 S&W is just as accurate as my Ruger Blackhawk in .357 Mag...For dispatching dogs, both work but the Glock holds more ammo but isn't legal here in NC for deer...