Following them entering the facility a couple of days back, dozens of police officers are inside Green Hill today still identifying and numbering over 2,500 beagles.
Rangers said three people were under investigation for animal abuse and neglect, and that the dogs would remain at the compound for now.
The raid comes three months after a dozen anti-vivisection activists entered the facility to rescue puppies.
“It's the first good news of the year and I am happy it's coming from Italy,” French ex-film star and animal rights activist Brigitte Bardot said in a statement.
“This dog farm of shame must permanently close its doors because we have no right to abandon thousands of dogs in hell,” she added.
The Italian senate is currently reviewing a provision that would bar the breeding of dogs, cats and primates for experimentation.
For images of the police raid on Green Hill, visit tinyurl.com/7zdu8c9