Chasing Shadows

Question
My Cairn terrier is a 5 year old male. He started chasing shadows three years ago. He is much more obedient than he used to be since this began and seems to really only get bad when people come over. With my boyfriend or I we can get him to stop within moments. I love my dog but it is very irritating and it seems that he is in distress. I have tried redirecting his attention with toys, treats etc. but it is hopeless if we have company. I am up for any suggestions.

Answer
I'm assuming the dog chases shadows a great deal, even when alone with you and the bf? If the dog displays this behavior only when guests are present, it's most likely an attention getting behavior (rewarded); if he does it more frequently, it may be more serious.  Dogs do develop obsessive compulsive behaviors and shadow chasing, tail chasing, running in tight circles, all are symptoms; there are also low level seizure disorders that can cause visual disturbances that the dog then generalizes to its environment.  You will want to take this behavior to the veterinarian.  Basic neurological examination and opthalmological checkup should be done.  If the dog's behavior is common (not only when visitors are present), there are medications the dog can be given to reduce the anxiety that's causing the compulsive behavior; it's quite difficult to diagnose neurological problems, but that doesn't mean it can't be done, and there are medications to control low level temporal lobe seizures.

Meanwhile, whenever the dog begins this behavior, put a lightweight leash on him and simply restrain him next to you, calmly, with no words, no touch, no commands of any sort, no eye contact, etc.  Leash restraint calms this sort of anxiety driven behavior and the dog should be visibly calmer.  Let's see what the veterinarian has to say, then repost.