I had something similar happen, although I was the one whose car was damaged. I'd not bothered to get minor damages repaired when an elderly couple backed into my properly parked car in the Home Depot parking lot. They never looked in their rear view mirror as they backed out. Tried to drive off, but I managed to stop them. She accused me of trying to scam them, depsite their paint on my car and mine on theirs. Said she saw no damage. Police would not come as the parking lot is privte property. I did get their insurance information and called my company. Quite upfront about the fact that there was some previous damage as well as the current. The adjustor could tell the difference. Anyways, yes, they paid for the damage THEY caused, some of which repaired previously damaged portions, but they did not pay for anything that they did not damage.
Call your insurance company (if you haven't already) and report the original accident. Describe the damage. Then tell him about the dog scratches to your car and the new accident. The sooner they have an adjuster look at his car, the more easy it will be to determine the old damage. If they will not let him assess the car, he will probably give up jhis rights to a claim.
Call your insurance company (if you haven't already) and report the original accident. Describe the damage. Then tell him about the dog scratches to your car and the new accident. The sooner they have an adjuster look at his car, the more easy it will be to determine the old damage. If they will not let him assess the car, he will probably give up jhis rights to a claim.