Hi Sheryl, welcome to the Nature Hounds! Hope to meet you and your 3 Jacks out on a walk soon. Welcome aboard!

Yeah. Digging under is dangerous. Check with your utility companies to see if you can dig there. If so, you might consider concrete poored about 2 feet down. You might need a city permit as well. I've seen this done at the ADL and digger dogs had been working the area for years. Eventually someone is going to get through the other side, but it will definately slow them down. Of course the best thing for a an escape artist to never let him/her alone outside.

Hi Cheryl. I have a weeny dog. Weenies and JRTs are bred to dig (earth dogs). So I suggest redirecting rather than curbing. I suggest a sandbox or sandpile or sand pit. Encourage your dogs to dig there by burying toys. If you catch them digging up the yard, just happily call them over to the sandpile. I've even started digging myself to get the dogs digging.

Be carefu lof what sand you use. There is a brand at one of the home supply stores that has a label that says it causes cancer.