Animals also don't have the social stigma of vomiting that humans do. Sometimes they'll vomit for basically no reason at all, because there's a low "cost" to doing it.

One time my dog and cat both ate some human food which was perfectly fine for them, but the cat didn't like the flavor. So the cat vomited. The dog looked at the cat, looked at the food, looked at the cat, and then vomited also.

Then the dog finished all the food and was fine.