My advice is don't do it. Digging around in a soft substrate, eliminating and then covering it up is how a cat's natural instincts work. Having him jump up on the toilet and eliminate while trying to straddle the seat is not natural. In the many years I've been doing behavior consultations, I've comes across many, many cats who have developed behavior problems after the owners attempted toilet training. Things go well while they're using the so-called training kit, but afterward, when it's just the cat vs. the toilet -- we're talking stress! Also, once you do this, it will become very confusing for your cat should you ever have to board or hospitalize him. Toilet training means the toilet lid must always remain up. That may seem like a small thing, but if you have guests over they might not remember to do this. Additionally, I think toilet training creates more of an odor problem than the litter box. And, I've seen many cats, even after being toilet trained, lose their balance and end up in the toilet. For a kitten, this can be life-threatening. Stick to what's natural. If you scoop the litter box twice a day and keep the box clean, both you and your cat will be much happier.
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