Does the prohibition on causing tzar baalei chayim (paining animals) preclude acts which only cause an animal mental anguish, such as scaring them, or it is limited to physical pain?
Yad Efraim Yoreh Deah 36:14 discusses the trauma of chickens seeing other chickens slaughtered. He says that this causes the chickens much distress and they become treifos from their lungs drying out from fear. He also says that in slaughter houses, animals should not be slaughtered in plain view of other animals because it is Tzaar Baalei Chaim. He concludes that Tzaar Baalei Chaim includes causing fear and scaring animals.