Well, I guess it is just their nature. Many dog's were and some still are taught to hunt creatures, but I believe it is their playful nature! My dog also chases shadows at night, and also chases lights, like if you shine a torch around on the floor. I don't really think there is an exact answer to your question, but I do hope I have helped a little.
I would let the dog chase shadows. It is merely a way that the dog is choosing to entertain himself. I use a laser pointer and have my dog chase around the laser pointer, she loves it and it is a great work out for her.
Entertain them another way. Divert their attention with another game like toss. If it persists, you may want to visit your vet and see what they suggest you try.
Chasing Shadows - album - was created in 1986.
Chasing After Shadows... Living with the Ghosts was created on 2010-05-18.
The cast of Chasing Shadows - 2012 includes: Jose Rosete as Detective
The cast of Chasing Shadows - 1991 includes: Hugo Gryn as Presenter
The cast of Chasing Shadows - 2014 includes: Alex Kingston Reece Shearsmith
The cast of Chasing the Shadows - 2009 includes: Vicki Monroe as herself John Zaffis as himself
not out yet :(
Chasing the Shadows - 2009 was released on: USA: 2009 USA: 23 April 2009 (Charleston International Film Festival)
Aidan 5 - 2009 Chasing Shadows 1-3 was released on: USA: 31 December 2010
Pit Pony - 1999 Chasing Shadows 1-41 is rated/received certificates of: USA:TV-G
The cast of Dogs Chasing My Car - 2006 includes: Francisco Nascimento
you like dogs so you can play chasing the sun