E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
seems to refer to age more than to any specific animal. Thus, boars of the second year, sheep between the time of their being weaned and shorn, colts, and bullocks a year old, are all called hogs or hoggets. A boar three years old is a hog-steer.
Some say a hogget is a sheep after its first shearing, but a hogget-fleece is the first shearing.
To go the whole hog. An American expression meaning unmixed democratical principles. It is used in England to signify a thorough goer of any kind. In Virginia the dealer asks the retail butcher if he means to go the whole hog, or to take only certain joints, and he regulates his price accordingly. (Men and Manners of America.)
Mahomet forbade his followers to eat one part of the pig, but did not particularise what part he intended. Hence, strict Mahometans abstain from pork altogether, but those less scrupulous eat any part they fancy. Cowper refers to this in the lines:
With sophistry their sauce they sweeten,
Till quite from tail to snout tis eaten.
Love of the World Reproved.
Another explanation is this: A hog in Ireland is slang for a shilling, and to go the whole hog means to spend the whole shilling. (See HOG.)
You have brought your hogs to a fine market. You have made a pretty kettle of fish.
You have brought your hogs to a fine market.Howell (1659).