Well, since in DF2010, the damage calculation has no arbitrary multipliers like a "damage value", and all the damage is calculated through a combination of a creature's size/ strength/skill and the geometry/size/material of their weapon, I imagine that training an animal for war just increases their skill as opposed to raising a nonexistant value. As far as I understand it, there is no way to change how deadly a trained animal is without making its untrained form equally more deadly.
That being said, trained Cave Crocodiles and Giant Desert Scorpions can still be pretty damned deadly, but I doubt trained wolves will ever be deadly unless you mod the bejesus out of them. Historically, Wardogs were really only dangerous in warfare as they would force an enemy to break formation, scare their horse (or in some rarer cases de-horse them), or distract them--they basically served more as distractions than deadly adversaries. If you use them as distractions, you'll find they do a great job of it in DF (many a time has a gobbo slain or mutilated a wardog only to be killed in turn by a soldier).An armed and/or armoured human has little to fear from a war dog, let alone a smaller, scrawnier wolf, so just bear in mind that the game is actually pretty accurate in terms of its portrayal of a wardog's role.