Dogs are tougher than most people give them credit for (ever seen a coyote with a first aid kit?). I wouldn't concern myself with the cactus. Most dogs won't even pay them any attention, and if they do, a cactus has a built in training device. As long as a dog has food, water, shelter and something to keep their mind occupied, they don't need much else. If your dog is inclined to bark, buy a bark collar, a few shocks from that and the barking should stop, your neighbors will appreciate that. Bring plenty of bags to pick up and dispose of poop.