There doesn't seem to be a goal outside of killing the enemies, and once it looked like I'd done that there wasn't anything further to do. If there was a level exit or the like, I couldn't find it.
Given the ranged nature of the enemies and the player's own way of attacking, it was rarely necessary to get anywhere close to the enemies, so for a while I didn't realise the pet could attack. The design of the game worked against it being useful.
I'd also recommend looking into raycasting or the like for determining where you're shooting, as having to click the enemy themselves detracts from the in-the-moment action of pointing and shooting.
All that being said, I love my dog an I'm glad he was there