RSPCA knew dodgy puppy breeder for decades

A dodgy puppy breeder whose property was raided this week was known to the RSPCA for almost two decades but couldn't previously be charged due to deficiencies in animal cruelty laws.

Some 120 dogs and puppies are being cared for by the RSPCA in Melbourne following raids on two properties in northern Victoria on Tuesday.

RSPCA Victoria chief executive Liz Walker says one of the breeders was known to the animal welfare group for 16 years.

"We got a tip-off in 2010, we went in 2011 and at that point in time we had 33 animals surrendered to us," Dr Walker told 3AW on Thursday.

Legislation in place then meant charges couldn't be laid, but changes to the code of practice for breeding businesses in 2012 means the owner can now be prosecuted for animal cruelty, the RSPCA chief said.

"We are confident that we will have charges laid - absolutely."

Owners can be jailed for two years and fined almost $75,000 but the RSPCA is more realistically hoping for banning orders prohibiting domestic animal ownership.

Dr Walker on Thursday revealed the current investigation had been running since late 2015.

The animal welfare group had a team of 21 people, including eight inspectors, in Longwood on Tuesday.

Police officers and local council employees were also involved in the raids.

The 120 rescued dogs - including spaniels, Chinese cresteds and chihuahuas - are now being cared for at the RSPCA animal care centre in Burwood.