Whatever the cause
Whatever the cause, it isn’t very nice to scare your pets. And it’s potentially very bad for them.
“If you cause stress to an animal that’s probably not a good thing,” Goldman told National Geographic. “If you do it for laughs it makes me question your humanity.” Animal behavior specialist Dr Roger Mugford also told Metro, “I think that the reaction is due to the novelty and unexpectedness of finding an unusual object secretly placed while their heads were down in the food bowl.”
Scaring your pets — for example, by tricking them into thinking a deadly predator is nearby — can cause them to injure themselves or break something once they try to leap away, and it can lead to long-term stress. Experts say it’s best to introduce new objects in a pet’s environment gradually.
Basically, don’t scare your pets.