In the drought animals starve! Warthogs that are old and weak struggle to find enough food to keep themselves sustained during this period.. This is where the Wild dogs (although it be in their own way) kind of help the old animals by having a relatively quick death in stead of dying slowly by starving to death.
This video is not for everyone and a lot will cringe but it's nature, to see the awesome teamwork of the dogs and the strength and resilience of the warthog is amazing!