Dogs and other animals like to dig where bulbs are planted. To keep them from digging up the most effective technique is to cover the planted area with chicken wire. Simply unroll the wire and weigh it down with something heavy to hold it in place during the fall and winter months. Then cover it with mulch. Keep an eye on the area in the spring, and when you see the tips of the leaves emerge from the ground, remove the wire and store it until next fall.