"According to our inspectors, the stench was indescribable," said SPCA Auckland executive director Bob Kerridge.
On entering the unit the inspectors and police were confronted by a swarm of flies and strong ammonia fumes, making breathing difficult and causing their eyes to water.
Inspectors found 19 cats with a number suffering from serious eye complaints, infections and other serious conditions associated with ill treatment.
They found a further 23 cats imprisoned in the one-bedroom downstairs unit, which was littered with faeces and urine.
"These cats were living in intolerably disgusting and unhealthy conditions requiring immediate action to improve their circumstances. Many needed urgent veterinary care and sadly not all of them were able to be saved," Mr Kerridge said.
"This is one of the most harrowing and foul cases of animal neglect on a massive scale that we have encountered. I would like to pay tribute to our dedicated inspectors who had to deal with some very distressing conditions that went well beyond the call of duty."
Ms Kondratyeva said she was responsible for the daily care of all cats on the property, owned by Donald Cruickshank, who was earlier this year convicted on the same charges relating to these cats, along with 38 dead cats discovered in the kitchen fridge and freezer.
An outdoor caged area was discovered, as well as another above a stairwell covered in cat faeces and urine that led to a locked downstairs unit.