People that abuse and neglect animals like this should be covered with hot tar on a hot summer day, strung upside down near a pile of fireants; with wild coyotes nearby and vultures waiting to dive in.
The dog I have right now looked very much like this one...not nearly as bad, of course, ......but he had horribly matted hair, nails that hadn't been clipped in a very long time, and general poor health. It was apparent that he had been out on the run for a very long time.
It took a groomer a long time and it took me a great deal of money to get him tamed and vetted.