I've done some testing. Watching damage done both with and without enhancements by beastmaster wolves. There was no change between 0 enhancements and 4 Atk enhancements. There were no solid numbers for me to look at just watching attacks. Then I noticed speed and jump were solid numbers. So I tried it.
0 Enhancements 21.48 run speed.
1 7.5% enhancement 21.48 run speed.
This was the base speed, not after it's own buffs. I didn't write them down but they also didn't change.
Add: Did some additional testing. Damage mods do work. Must have been my mistake. However While testing one wolf died. I enhanced the wolf speed and summoned a new wolf. Targetting a distant enemy I sent them on attack. 20% run speed boost they both ran the exact same speed.