When your dog shakes and drools excessively, it's usually because he or she is experiencing extreme anxiety or stress. If your dog is shaking and drooling for no apparent reason, contact your veterinarian immediately. You should consider a visit with your veterinarian every time your dog shakes and drools. You may notice that your dog has started shaking and drooling when he or she is anxious or excited. It's important to note that this behavior isn't always caused by something bad happening. It's normal for dogs to shake and drool during times of high emotion. This type of behavior can be triggered by the excitement of playing fetch, meeting new people, or doing a fun activity. When a dog experiences these emotions, they will usually shake and drool until their body temperature returns to normal.