In spite of the dryness here, that walnut next door just seems to grow like crazy. I've cut it back once since I moved in, mostly because it was trying to puncture the roof of my shed. (Before I put a solid roof on it, it was just plastic. Take a look at the link and see how fast that walnut has been growing around the cactus.)
So, I got out there and cut it back again today. Here's the before shot:
And here's the after shot:
The gloves I wore weren't as thick as I thought. My hands have needles in them. I've never liked cactus. I'm still surprised I didn't notice them and make their removal a condition of the sale.
I don't know how you prune the cacti. I just ripped off some of the pads from the prickly pear. They're unexpectedly heavy.