He said in an interview with Seventeen Latino magazine: “I cried the last day that Tai was on the set of ‘Water For Elephants’, and during the film, ‘March of the Penguins’.”
Robert – who stars with Reese Witherspoon in the film – claims he enjoys making movies with animals more than professional actors because there is less pressure.
He added: “I think I have more affinity with animals than with people. For many reasons, I prefer working with animals and children than with actors. Often when you’re working with actors, it becomes something almost competitive.”
Perhaps the reason why Robert became tearful when Thai completed her scenes was because they had got so close on set.
The Hollywood heartthrob previously revealed: "The first time I met Thai, I just got in her mouth. It just seemed like a good place to be!
"She had these huge lips and her teeth were all the way at the back so she just carried me around!"
In the film Reese plays circus performer Marlena Rosenbluth whose horse dies putting her act in jeopardy, until her husband - cruel animal trainer August Rosenbluth - buys her an elephant which leads her to find love with Robert's vet character Jacob Jankowski.