Adding ozone may be another approach. (links below)
You can go to the 'oxygen' site on curezone to find out more about ozone.
I have been using it for some time now and it is truly amazing.
Also, make your own food. Besides other dead, euthanized, and diseased
cats and dogs in commercial pet food, (there are no FDA guidlines), you
might want to stay away from any food that has wheat gluten in it. Any of the
'chunky or flakey' textured foods are made with wheat gluten. I had a horrible
'scooting' problem with my cat which stopped when I took the wheat
gluten out of his diet. Cats and dogs were never meant to eat wheat
gluten. It is also a major food allergen of humans.