Cats living in family home

Question
I have a neighbor in an apartment who has 5 adult cats living inside with them.  
Is there a regulations regarding the quantity of cats or pets that can reside in a
single residence.

Answer
Gene,

That depends on the specific municipal by-laws in your local area. If you suspect that the cats are being abused or neglected you can call your local animal cruelty investigation team to check things out. If the cats are spayed/neutered to prevent a population explosion and they're being properly cared for with all of the appropriate maintenance happening in terms of hygiene then I see no reason why it would be inappropriate to house 5 cats in the same home. Maybe it would help if I knew specifically what you are concerned about?