If her insurers have paid the bill, as it seems, they CANNOT claim anything other than ANY excess they might have had to pay.
They certainly cannot claimback any money, as it is not them who have been made "out of pocket", it is down to the insurers to persue a claim for this if they wish to recover THEIR LOSSES.
The dogs owners only suffered any excess(?) and can claim that.
House insurance will also cover acts like this from the attacking dogs owners, so the insurance co can also claim on this.
tabetha