Necromunda: Hired Gun

Assuming you kept the basic control scheme, pressing B will summon your dog, which is capable of attacking nearby enemies as well as performing a quick attack with an additional press of the B button. The dog has both health as well as a timer and will leave once either of those runs out.

My assumption is that the kills have to be quick attack kills however I am uncertain on that. If you are playing on an Xbox One (like I was) it seems that trying to upgrade the dog hard-exits the game, so getting this done sooner rather than later should be a priority.