Dear Kerry: The steam cleaner is only practical if you happen to have one or know someone who does. I suppose you could rent one, but then that would add to the cost and defeat the purpose of getting a used cat tree. Perhaps some do-it-yourself car washes might have one. It is a way to get something clean and more or less sterilized without having to use chemicals that might leave a toxic residue.
Someone mentioned using bleach and thought the toxic ingredient (chlorine), which is also what kills bacteria or whatver, would evaporate out. I am sure some of it will as the fumes are what is harmful to breathe when you are working with bleach, but unless you rinsed it very thoroghly (and that is hard to do wth carpeting) to get it all out, I'm not sure cats would find it user friendly. Maybe something like Novalsan would work OK and be less toxic?? Dunno...I've never tried it. The boric acid carpet powder is marketed by a company called Flea Busters. They may have a website you could order it from...I'll have to look on my jug and see if there is one listed on the label. I've also seen some powdered ant and roach killers that have boric acid as the active ingredient for considerably less at places like Home Depot. You just need to make sure there are no other ingredients or pesticides included that would be toxic. It should list boric acid as the only "active" ingredient and anything else in the product would be listed as "intert ingredients". The boric acid you might find at a pharmacy would probably be purified to make it suitable for making eye wash and thus much more expensive. I don't know if hydrogen peroxide, which can be used to clean wounds and doesn't smell, or sting the way alcohol does, is effective as a disinfectant or not. It is composed of hydrogen and oxygen and breaks down into water with the extra oxygen fizzing off, so while the oxygen can have a cleansing or bleaching effect, I don't think it is all that antibacterial. It does sting if you get it in your eyes, especially the strong peroxide used in hair colorings. Hope you can figure out a way to get the kitty tree cleaned satisfactorily so your cats can enjoy it. My cats LOVE their"trees" and the bunk bed. I have one very shy male cat among my healthy, adoptable rescues and after I got them a cat tree, Bronson decided the top perch, which is about chest high on me, was HIS spot and when enthroned there, he will let me walk up and pet him and not try to run and hide. If he is on the floor, however, you cannot approach him. He feels more confident when he can be eye to eye or above me. Good luck! Sally in San Jose
