<human>: Asking for a friend "Snow" shown in this story. She's torn up right now about her dog who is injured, but recovering, and I wonder how she should best proceed.

Dog owner "Snow" is walking her 10 [lb] small dog "Happy" through their neighborhood.

They walk past "Regina's" house and Regina's 60 [lb] larger dog "Angry" runs out of Regina's unlocked door up to Happy immediately biting and breaking Happy's leash.  Angry then carries Happy a few houses down, throws her around like a rag doll, and leaves her unmoving for dead on a different neighbor's lawn.

Regina gives a ride to Snow and Happy to a vet. Happy had numerous broken ribs, receives a blood transfusion, surgery, and a number of stitches.

A day or so later Snow gets a vet bill around $7k, and asks Regina for reimbursement. Regina offers a few hundred, but is not interested in paying the full amount.

Snow has also since filed an animal control report and spoken with some of the neighbors. Although it seems there are no other witnesses. Snow's plan from here is to sue in small claims, though she's open to hiring a lawyer and suing in grown up court.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Attacker dog, "Angry" runs out of open door attacking Victim dog "Happy" in residential neighborhood. Results in the $7k vet bill which Angry dog's owner is not willing to pay.