The Wild Beasts (1984) Uncut
When PCP gets into the water supply of a large zoo in Frankfurt, Germany, it soon becomes blood and gore galore as the zoo animals go crazy, break out of their cages, and go on a homicidal, nigh time rampage through the city killing any person they see starting with sewer rats killing a number of strangers, then tigers, cheetahs, lions and even elephants join in the killing spree. Zoo veterinarian Rupert Berner, his scientist girlfriend Laura, along with a local police officer, Inspector Braun, try to find a way to control the murderous animals and stop them before they decimate the entire city in this "nature strikes back" horror film.
http://www.youtube.com/watch?v=QYRnOZGxGRU