By now, it's pretty common knowledge that most of the zombies on The Walking Dead are portrayed by real people who are all gussied up for the apocalypse with prosthetics, makeup, and the occasional visual-effects treatment. Those extra actors might not always be recognizable by the time the team is done with them, but, hey, they can still totally have a "Hi, Mom" moment on Sunday nights and tell stories about chowing down on condoms full of red water at Thanksgiving. Good times.
With some of the animal scenes, though, the team can't always go as au naturale because, ya know, not all animal handlers have trained their four-legged friends in the art of undead invasion responses. Instead, they've turned to CGI and other special effects to make the scenes happen, whether to avoid danger or just getting the wrong reaction out of the creatures.
With Shiva, the tigress who mightily stands guard for King Ezekiel, this is especially necessary as the consequences of a misread moment on set with a real ferocious feline might be lethal for the cast and crew involved. So, although her growling and pouncing all seem pretty authentic, she's definitely been a product of cinematic magic on the show.
For some scenes, the badass Bengal's body has been added in during postproduction, after the human actors shoot their scenes and play to her invisible reactions. All the effects team needs to insert her there is a frame of physical reference squared away to make space for her size, which is how the scene when King Ezekiel is first introduced, with her at his side in the gymnasium, shakes out.
For other scenes, though, a physical actor in a blue suit has had to stand in for the character and perform all kinds of acrobatic stunts to simulate her attack movements. As Chandler Riggs, whose character Carl would be mince meat if not for her sudden arrival to stifle Negan's swing, put it, "When shiva came in clutch, it was literally a guy in a blue suit jumping off of a trampoline and tackling the guy."
For the pictures-or-it-didn't-happen crowd, AMC has released the receipts to back up his assessment of the otherwise dramatic moment with a behind-the-scenes look that's oddly hysterical and simply cannot be unseen.
You can't spell catharsis without cat.