Well, if we’re using our own dogs, somewhere on here is my thread about how the ONLY thing my dog Tucker EVER noticed on TV was an interview with George Bush, and he growled every time Bush came on screen. He would stop when the visual switched to the interviewer, then start when it switched to Bush. 100% true. He never before or after responded to anything on TV.
Dunno about dogs, but one of my cats used to watch the TV if there were cats (including lions) on it. I once turned off a documentary about lions (I was leaving–otherwise I’d have watched it) and the cat stood up and started meowing at me. I put it back on for her and she was happy. Not sure about still images. And totally not sure about dogs.
Here’s a study that might be of interest.
He was reacting to your body language, obviously.
Regards,
Shodan