This was American college slang of the 1860’s. Whether or not it originated at Yale, it was so credited by Lyman H. Bagg who, in his Four Years at Yale (1871), wrote: “Dog, style, splurge. To put on dog is to make a flashy display, to cut a swell”, and the latter expression in the definition could be defined, “to appear important.”
But it was then that the Blenheim and the King Charles spaniels were at the height of aristocratic popularity. Nothing could appear snootier, more high-toned than those dogs.
The source of college slang even of today can be little more than guesswork, and to go back eighty-five years is necessarily conjectural.
Put on (the) dog dates back to American college slang of the 1860s and is recorded in Lyman H. Baggs Four Years at Yale : “Dog, style, splurge. To put on dog is to make a flashy display, to cut a swell.” At about the same time, the related adjective doggy was a popular slang term meaning attractively stylish; costly; fancy.
How to Use it in a Sentence
There are several sentences that can be used to illustrate the use of the idiom put on the dog. A few examples of sentences that include this figure or speech are as follows: