Unleashed dogs fight, who pays?

my dog bit another dog, both dogs were unleashed but when the fight took place the other owner wasnt about. my dog is a lab and he has a smaller dog. his dog instigated the fight but it is deaf and blind. who pays for the bills?

It's difficult for me to understand how the other dog "instigated" the fight if he is both deaf and blind. How would he know where your dog was to attack him?