The Riverside Press-Enterprise said animal control officers with a warrant swept down on the home in Menifee in the Sun City area last Thursday.
"The smell was horrendous," officer Monique Middleton told the newspaper. Middleton works for the non-profit Animal Friends of the Valleys, which provides animal control services for Menifee.
The officer said the home's owner, an unidentified man in his 50s, had been trying to rescue unwanted cats but things got out of hand.
The cats were kept indoors, were well-fed and had all been spayed or neutered, Middleton told the Press-Enterprise, but many had an upper respiratory infection, probably from living in close quarters.
If the man is charged, he would most likely face a misdemeanor count of animal cruelty, Middleton said, but that would be up to the Riverside County district attorney's office.
She said the man originally agreed to cooperate with officers in removing the cats, but backed out. "He was just afraid his cats might get put to sleep," Middleton said.
She said the couple will not be allowed to return until the house has been thoroughly cleaned.