A Pet reptile was used as guard "dog"

Could be that the alligator has not been well looked after and that's why it was found dead the next day.

I had to laugh at the story about the venomous snakes being stolen along with the jewels they were supposed to be hiding.

I have heard of geese being effective guard dogs because they announce the arrival of any stranger with their honking, and a flock of geese can be quite aggressive.