system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do animals not get as regularly sick as humans? Or do they?

I'm not sure if this is an incredible stupid question.. I grew up with dogs and cats but I've always wondered why they don't (or atleast don't seem to) get sick as often as humans i.e. cold, flu etc.
gpt
Most animals do become ill with similar frequency to humans.  The difference is that they can't complain in language, so it's hard for us to tell when they're ill.  In the wild, there is no one to take sick or wounded animals to any sort of health care, so they tend to die, and the healthier ones get to live long enough to reproduce, thus encouraging (through evolution) more effective immune systems in their offspring.

Evolution FTW!