Certified GKH Gardening Expert
Yes, it's possible that slugs are attacking your bulbs, or more specifically, the green foliage of the bulbs that comes up in the spring. They might eat it before it pushes above the soil, so you may never see it. Please see this article on control methods and plants that slugs avoid:
Mammals such as rodents can also eat bulbs. Here's how to prevent that:
Also, make sure the bulbs are the right kind for your climate (check their winter hardiness) to make sure they will not freeze over the winter.