Good Morning and welcome to Just answer. I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
This is a common problem in many areas. You can cover this box with a cover that stops the cats from getting into this box. There are also commercial preparations that you can purchase at the pet store that will discourage the cats from using this box and many have been successful and are not harmful to cats or children. There is a homemade product that is included in the site I will give you that will discourage cats from using this box that includes garlic and onion.
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