NOTE: The preventative shot has been fixed in patch 12/12/17 - PC 1.37.35.1010 / Mac 1.37.35.1210 but not the wellness treat.We're a little unsure whether this is an actual bug or just that this has a long timer.
Giving a pet a preventative shot from a vet causes a pet to continuously be in a scared, negative mood.Giving a pet a Wellness treat seems to cause the same.
Work around using cheats:
1. Enable testing cheats by opening the console (Control+Shift+C and typing in testingcheats on)
2. Get the SimID by the pet affected by the bug by typing in the command sims.get_sim_id_by_name FirstNameofPet LastNameofPet
3. Write down the sim ID written in the console, it'll be a 19 character long string
4. Remove all moodlets from your pet by typing in sims.remove_all_buffs SimID, e.g. sims.remove_all_buffs 1052442116385935975
Bug Report (click)Work around in-game:
1. In some games feeding your pet another wellness treat works
or if it was the preventative shot that caused it in the first place, giving another preventative shot.