E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Catch your Hare (First).
It is generally believed that Mrs. Glasse, in her Cookery Book, gave this direction; but the exact words are, Take your hare when it is cased, and make a pudding, etc. To case means to take off the skin. Thus, in Alls Well that Ends Well, iii. 6, we have these words, Well make you some sport with the fox ere we case him. Scatch also means to skin, and this word gave rise to the misquoted catch. Though scatch and case both mean to skin, yet the word used in the book referred to is case, not scatch. Mrs. Glasse was the penname of Dr. John Hill (17161775), author of The Cookery Book. (See CASE.)
Bracton, however (book iv. tit. i. chap. xxi. sec. 4), has these words: Vulgariter dicitur, quod primo oportet cervum capere, et postea (cum captus fuerit) illum excoriare.
The Welsh word cach = ordure, dung, and to cach (cachu) would be to clean and gut the hare.