An Etymological Dictionary of the German Language/Fuchs
Fuchs, m., ‘fox, light bay horse, cunning person, freshman (univ.)’ from the equiv. MidHG. vuhs, OHG. fuhs, m.; corresponding to Du. vos, AS. and E. fox; Goth. *faúhs-, m. (weak subst.), is not found. The s is a masc. suffix, as in Luchs; it is wanting, therefore, in the older fem. form, OHG. foha, MidHG. vohe, f., ‘vixen’ (also ‘fox,’ equiv. to Goth. faúhô, f., ‘fox,’ OIc. foa, ‘fox’). OIc. fox, n., is used only in the figurative sense of ‘deceit.’ The ModHG. fem. form Füchsin corresponds to AS. fyxen, E. vixen. Goth. faúhô, f., from pre-Teut. púkâ, makes it appear possible to connect the word phonetically with ModHG. Vogel, Goth. fugls, pre-Teut. pukló-s, in case Sans. puccha, ‘tail, train,’ is of a cognate stem; Fuchs and Vogel, meaning ‘tailed creatures,’ is quite possible. At all events, there is no connection with Lat. L. vulpes.