The Wife had an awesome idea, so I am stealing it!
Arrow of Animal Summoning
Wondrous item, uncommon
This arrow is made from the antlers of a stag and carved with runes. When a creature fires this arrow, they may whisper the name of an animal that can be summoned by conjure animals. If the arrow strikes a creature, the animal is summoned as per the spell and attacks the target. The summoned animal stays summoned until it is killed, the spell is dispelled by a spell, or the target is killed. The spell is not ended otherwise. The arrow becomes a regular arrow after the spell ends.