Nice, but what feats does he need ?
I'm guessing that Wild Cohort doesn't cut it.
That just gives him an Animal
Ed: will Dragon Cohort suffice ?
By RAW, no. Dragon Cohort only works on a specific list of dragons within the Draconomicon. This includes only metallic and chromatic dragons as well as a couple others (pseudodragon, wyvern, dragonnel, and spiked felldrake). I think its fair to expand the feat to include other choices, like half-dragon rhinos, but it requires DM approval.
Also, how drunk was the dragon when it decided a half-rhino kid was a good idea?