jumping at shadows

Question
hi'my dog is a lab x terrier is 11months old i got him in shelter when he was 12 weeks old was very shy towards humans and would hide when some one came about house,i had him nutered and microchiped,he is now house trained and do's everything he's told i.e sits,fetches,rolls over,and barks when strangers come to house, perfect dog to have? except when we are in house it jumps up in the air and pounces on shadows no matter where they appear floor, settee, walls. is this the terrier in him or is it a faze its going through.regards

Answer
During doggie adolescence (7 to 14 months) the dog's brain is still developing (just as in humans up to age 22+.)  It's possible your dog is responding to physiological changes; it's also possible your dog is simply playing with an object he can't cognitively define.  The dog's eyesight is very nearsighted; contrast (as in shadows, particularly well defined shadows) may provide an unusual stimulus.  However, this can also be a sign of neurological problems.  These problems are notoriously difficult to diagnose, often requiring expensive tests that don't necessarily provide an answer.  Do not reward this behavior in any way, simply ignore it.  If you pay extra attention to the dog during these forays (as in laughing, calling his name, attempting to dissuade his behavior, or any reaction at all) it may increase.  Simply observe from a safe and silent distance for a month or so.  See if this behavior self extinguishes.  If you find that it increases anyway, observe the dog for other signs, such as reaction to sudden high light, circling, staring into space, attempting to make back contact with such things as end tables, etc.  These might be symptoms of low level seizures.  In any case, bringing this behavior to the attention of a GOOD veterinarian can't hurt.