I don't recall seeing such a feat. Its possible there is one though since the number of 4e feats is pretty huge now.
Seems to me it wouldn't be all that hard to come up with a reasonably balanced feat to do what you want. So far I think Thundertusk Companion is the only feat that boosts one specific type of companion. I'm guessing MP2 may throw in a few more of these and maybe other options for beasts.