Just because prescription and over-the-counter (OTC) medications are marked childproof doesn't mean they're dogproof. In fact, most dogs find it way too easy to chew through plastic pill containers if given the opportunity.
And many the most common drugs and supplements are potentially lethal to dogs, even in relatively small doses. Keep your pet safe by storing all meds, vitamins, and supplements in a secure cabinet that's out of your pet's reach.