If you read nothing else on this page today please just read this: Do not use laser beam toys with your puppy or dog. The results can be catastrophic, beyond what many would even imagine.
The above video (not my video) is an example of a puppy being played with through the use of a laser toy. To the untrained eye it can look like a gentle and fun exercise, but if the puppy King Charles Spaniel in the video continued to be encouraged to chase a little red dot there is a very high chance s/he will develop light reactivity. Light reactivity can be an extremely serious compulsive behaviour. Lucky for me, my Yorkie cross only has it mild.
The little red dot from a laser beam can never be caught which is what can make it entertaining for us humans, but to our canine friends it can make it extremely frustrating, the game never ends. When we have put the laser away the game is finished to us because we understand the concept of the gadget producing the laser light. Dogs don't. The laser light very easily becomes generalised to other things: reflections of watches/mirrors/phones on the walls and ceilings indoors, reflections of car beams on windows outside, the moon in the sky, flashing lights in the sky from airplanes or cranes, water shimmering, fireworks, the list goes on.
My dog is reactive to light with everything creating light, moving or otherwise, sparking up a reaction in him: barking, chasing, shivering and obsessively monitoring it. I am lucky that his reaction is mild. Dogs can become seriously injured throwing themselves into walls to "catch" the light or giving chase compulsively into roads for example.
A year or so down the line and it is possible to redirect my dogs attention now. If he sees a light he will, for the most part, look at me for something good that ends the game before it has even begun. There are ways of helping your dog overcome this compulsive behaviour but as with everything, prevention is better than cure.