Its a zombie apocalypse but it's pretty grounded. They have a ton of science facts in collectables explaining how the Autophage works and it's realistically portrayed.
You can damage zombies hands with your weapons. This is hard to avoid as they reach their hands out towards you and it is easy to hit them when you are attacking them
There are hospitals and experiments but its just an environment. However there are audio logs mentioning experiments on dead zombies. There isn't a traditional hospital though or any real scenes in the field ones.
There is an audio log implying the death or significant harm to a Dolphin at the hands of a zombie. This is not seen, and the Dolphin can be heard crying.
Audio files indicate zombies are the only ones that abuse or cause major distress to animals. You also later find out a side character’s dog was killed by their ex-husband.
No animals are visibly present, however, there is an audio recording that has a cat and a zombie. While the cat does run away, it is in distress and it is unclear if the cat was bitten or safely escaped.
Near the beginning of the game, the player character is chained to gym equipment with handcuffs because the other characters are afraid the player character will turn and bite the others. However, the player is informed the handcuffs are toys and the character frees themself.
The Santa Monica pier map has clowns on it, with the whole pier having a clown theme, and one of the variants of the slobber and butcher zombies are dressed as clowns.
Lots of audio files that play automatically include a zombie sound in the background. Zombies in general make lots of different sounds including gurgling and screaming.