I posted before asking for advice about my elderly cat's kidney disease. Many thanks again for the helpful replies. I'm hoping that you may be able to advise me on an issue arising from this. She has obviously been drinking and urinating much more than before; as a result, the litter box now smells very strongly and it permeates the whole house. It is especially bad when we come in from work. We use the wood chip litter and do change it every day, but the smell of urine is still overpowering! We've checked the floors/rugs, etc, but the odour is definitely from the litter. The vet suggested an ioniser. I was wondering if anyone has tried one or had any other suggestions for a different kind of litter that really soaks up odours? We will be having house guests soon and I don't want them to have to smell the cat urine! Thanks in advance.