Your dog may feel and act more lethargic than usual, especially when you first start giving them CBD. They may also drink more water because CBD can decrease how much saliva dogs produce (much like cotton mouth in people). If you give them a high CBD dose, they might experience a drop in blood pressure, which causes lightheadedness, weakness, confusion, or falling. The most important thing to pay attention to are signs of THC toxicity, especially if you choose a full-spectrum CBD for your pup.