This is the bulb of Erythronium dens-canis which is the European species colloquially known as Dog Tooth Violet. Other members of the genus (mostly North American) share the same common name for the bulbs' resemblance to dogs' teeth.

 E. dens-canis looks to be about the right size to be found in a large dog's jaw. Then again the American cultivar E. Pagoda would be a huge hound indeed for a gnasher like this...