City News Service says 69-year-old John Howe of Santa Ana entered guilty pleas on Monday and was sentenced to three years of probation.
Howe's wife and three other relatives still face charges.
Prosecutors say the adults and two girls, ages 6 and 12, lived in a home that housed an illegal cat rescue operation. Neighbors complaining of foul smells led police there in February of 2011.
Authorities say the home was filthy with cat hair and excrement, flies and roaches.
Some 20 cats had to be euthanized. The rest were adopted.