They are forced to relive whatever trauma they experienced through different psychological symptoms. It is evident, through many articles like the ones mentioned above, that animals can indeed suffer from Post-Traumatic Stress just like humans.

How do animals handle trauma?

Scientists have made a fascinating discovery about the way animals in the wild let go of fear and stress. Because they are able to release it and move on, they are free of PTSD like symptoms. Without this ability in the wild, they would wander around shut down, uptight or confused . . . and they would not survive long.

What animals get PTSD?

New research shows that elephants and other animals can suffer from PTSD.