I am wondering if it was made by one of the European gun manufactures. The MFG on the top is wide apart and they may have marked it as such to get around the Colt name rights. I have never seen a Colt that looks like it. Colt did license K.K.P. in Austria around 1850 to build some small models. Look to see if the gun has any other markings. I have never seen the name Puppy on any of there guns. Some foreign countries did build some counterfeit guns that were marked Colt.
I googled "revolver puppy" and found quite a few images of similar revolvers to yours. Also some sites mention that both Belgium & Spain made various models with the name Puppy. I didn't see one marked Colt but several marked in the same location as your with Puppy.
There is a pistol with an identical outline to this one in A.B. Zhuk's Illustrated Encyclopadia of Handguns (fig. 1047) described as a "Bulldog" and attributed to Auguste Francotte & Companie, Liege. .320 calibre, 5-shot.
Years ago my dad brought home what he thought was a Smith $ Wesson breaktop revolver he won in a raffle. On top of the barrel it had For in tiny letters, then SMITH & WESSON in large letters, and then again in tiny letters Ctgs. The front and back markings were so tiny you didn't really notice what they said, but the Smith & Wesson stood out.