Take some fur of the cat (shed fur will do nicely). Tie fur into a bunch with some red thread (silk by preference, although cotton or even acrylic will do). Invoke the blessing of your patron deity. Place consecrated fur into a cannister (the following is imperative!). The cannister must be reflective on the outside, but NOT on the inside (If the cannister is reflective on the inside, it will focus malicious intent on the cats!). Seal the cannister with red wax (just a dab will do) Place cannister  next to cat's usual exit. Red is the color of  protection, silk is an insulator, the reflective cannister reflects malicious intent, the blessing is for extra whammy to the spell.