The picture of the reverse is so dark I don't dare venture a guess with just a sideways picture of an obverse.
I'm nowhere near an expert but it could be anything from a horse to a bull. Even I have a coin that looks similar: Histiaia, Euboia, Greece Bronze AE 12, BCD Euboia 455; BMC Central p. 125, 9; SNG Cop 537 var. (control), Oreoi mint, weight 2.325g, 12.2mm, 90o, c. 4th - 3rd century B.C.; obverse head of nymph Histiaia right, rolled hair, wearing wreath of ivy, pendant earring and necklace; reverse bull standing right, bunch of grapes (control symbol) above, IΣTI below. There are so many Greek coins with a four legged animal on its reverse, it would be difficult to pin point. Can you see any letters?
Thanks, Justin. I was just about to do that because it bugs me to see ID help pictures as uncropped unjoined poorly lit thumbnails Doesn't help a lot in this case though. @kokotko, it is helpful and often necessary to tell us the size and weight. Better images might help too. JBruce's guess is a good one if the size is in the ballpark. The reverse animal looks like a bull, horse, or dog. You might also look through CNG's archives and acsearch with search terms "AE hound Eryx" and "AE hound Segesta". If your reverse is a dog those are good bets.