1) A hunting dog which pursues its prey by scent.
1514 browght a grett multitude off dogges both grewhondis and ratches, Moor Monkton
1665 a strange noyse in the aire ... this winter called Gabriel-Ratches by this country-people, the noyse is as if a great number of whelps were barking and howling, Northowram. It was probably the source of a by-name given as a nick-name, although rache is also possible: 1298-9 domus Gilberti Racche in Halton.
2) A line down a horse’s face, usually said to be white.
1512 a trotting stag, blak, with a rache in the face, Well
1556 my bay stagge with a long Rache, Farnley
1617 my blew Dand horse with a whyte racke, Barmston
1689 one bay guelding with a black list and a white rache down his face, Middleton
1726 an Old Single Eyed bay Mare, a White Rach down her Face, Whitkirk.