My senior dog (12 yo Australian shepherd) is having anxiety attacks lately. He paces and pants and tries to jump on me and nose me and he whines and barks...general annoying behavior. He is keeping me up at night which is annoying, but my real concern is that he seems to be in mental distress. Clearly he is very upset and he can't seem to do anything to relieve his stress. Last night it started at about 9:30 PM and lasted until 3 in the morning. He was so stressed out for so long I was afraid he was going to have a heart attack. Are there any over the counter drugs or supplements that can help relieve his stress.