We have a digging patch for ours, which as a bonus was already in the garden when we moved in; it’s a separated into a digging part and a toilet area.
It’s basically an area that was dug out to about 18” deep and back filled with a mix of sharp sand and top soil. There’s a couple of posts buried in with rope attached for a bit of pulling practice and when we are going out then we use a pointy stick to poke some holes and drop treats down, it just needs raking over every now and again to flatten it out.
It still hasn’t stopped the little bugger treasure digging up all the bulbs from the garden though, she can just dig quicker now because of all the practice.