Yeah but that is a different case i think. My mare wasn't skinny and she was only found with one other horse. The SPCA was asked if they have seen her before and they said no. The always log all the abuse/starvation cases and she wasn't one of them.
She was also left on the ranch itself. There were no other horses(except for the dead one) but it was dead winter. She wasn't even left with a blanket or halter and she was unshod and only halter broke.
PS The SPCA was asked to take her but had no room. If there was a home found for her right away she would have been put down.