You can make anything in the game, including a very close approximation of a dog. If your game pulls creations from Spore's online library, you can encounter a dog or doglike creature, and you may be forced to fight and kill it. The odds of this happening are fairly low, but not impossible.
Your allies in creature stage can be killed and eaten, and you yourself can be eaten by other cells in cell stage. However, this isn't detailed and is often portrayed with vague meat chunks.
Tribal stage, and tribes in general, both in game and in the game's promo art, almost entirely consist of native stereotypes. At the start of civilization stage, the player is also actively rewarded with money or vehicles for destroying tribes.
Civilized creatures will make cartoonish screams under certain circumstances- though in certain contexts, such as dying to lava, or losing civilization stage, this can be mildly disturbing
There's religious nations in civilization stage, and zealots and shamans in space stage, all which have their own religions- Zealots especially talk about their religion a lot, though all these are pretty vague and purely fictional religions that are often poked fun at
There's occasional, rare, silly little eastereggs that reference spore being a videogame- but most people won't see them in an average playthrough thanks to how small and out of the way they are
There's some potential for the player to abuse animals (ie abducting them in your spaceship and beaming them to an inhospitable planet), but most of the animal-related violence in the game is in the context of survival.
Creatures that are screaming and on fire fall out of destroyed buildings. Some missions in the Space stage involve finding and incinerating diseased creatures with a laser.
In the creature stage, an asteroid impact can cause the screen to shake. In creature stage and space adventures the camera is prone to glitching out when you walk onto an unusually-shaped object.
An adventure in the DLC, which is mandatory so long as the player has the DLC and wants to ally with a Zealot empire in the space stage features a simplistic plotline where the player needs to kill tribe members in order to defend a priest and their church- said tribe members will sometimes say things like "leave our lands!", and the church is very obviously based off a christian church. Everything about the adventure paints the church and the priest in a good light. You could possibly play this off as satire, but with how spore portrays natives, that isn't likely
One of the first missions in the Space stage involves investigating a crashed spacecraft. However, no spaceships or aircraft crash on-screen since they always explode in mid-air.
Creatures beamed down into water will drown with a special animation, but you're not likely to see it thanks to how small creatures in space stage usually look, and the fact you can just. not do that.