Completely believable, have 3 rescue dogs, and each one suffered in different ways before landing up on our doorstep. Even though its been years for 2 of them , certain things still trigger a distress response in them.
For one its a complete fear of the bath, and wont even go into that room (people who rescued her say that the rest of the litter she was part of was drowned).
1 of the other 2 is agoraphobia, he will barely walk around the block before suddenly doing an abrupt turn and head home. Previous owners tried to ditch him and would keep him outside where he slept on the back porch, no basket nothing as a puppy.
3rd one is more recent Dec/Jan this year ,so far the only thing i can gauge is he hates being cold, and i mean really hates it. Has to be covered up and literally wrapped in a blanket, the moment he is, all you hear are little satisfied grunts emanating from under the pile of blankets every so often.
Previous rescue that has subsequently passed away, had spent many years outside living on the streets with some vagrants, hated thunder and lightning. Would shiver and shake and climb all over you when it happened. You literally had to cradle her until the storm had passed. moment it had she was off your lap. If you tried to pick her up normally she got quite snappy and was quick to nip, not enough to draw blood, but enough that you know where you stood.
So do animals suffer from PTSD ?, dont doubt it in the least.