Dear owner,
as a former PM, I must warn you about the life cycle of the flea, it takes 2 weeks for their eggs to hatch after the cat has moved on. I was sent to an empty premises as a sweet young thing (and returned to the office only after spaying myself with mortein.....)
Please get a fumigation clause stuck on to their new lease,.
After Kitty owner has moved on, I am sure you don't want your new tenants complaining about an infestation.
Good Luck!