You can deliver a toxic bite attack reminiscent of the viper.
Prerequisite: Wild shape ability.Benefit: You can spend a usage of wild shape to gain a secondary bite attack (at your base attack bonus –5 and adding half your Strength bonus) that deals bludgeoning, piercing and slashing damage equal to a dagger appropriate to your size (1d4 for Medium, or 1d3 for Small). In addition, the bite delivers a toxic venom (Fortitude save DC 10 + ½ your HD + your Con modifier; 1d6 Con/1d6 Con).
Special: If you already have a bite attack, it just gains the toxic venom part of this feat.
Source: Complete Divine, page 84.