If you read nothing else on this page today please just read this: Do not use laser 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 convenient 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. With the way the puppy was encouraged to spin, there is a risk of that becoming a compulsive behaviour also. Light reactivity can be an extremely serious compulsive behaviour leading to significant mental and physical ill health, or even death.
The little red dot from a laser beam can never be caught which is what can make it entertaining for us humans to watch, 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 that comes into our dogs vision daily: reflections of light off watches/mirrors/phones on the walls and ceilings indoors, reflections of car beams on windows/walls, the moon, flashing lights from airplanes or cranes, water shimmering, fireworks, christmas lights, the list goes on. Dogs have a faster reaction time to visual signals than we do, and notice minute movements that we ourselves may be unaware of. When they are taught to find light chasing stimulating there is no end of lights that may trigger that response and it can also be generalised to shadows as well.
My dog was exercised with a laser pen 5 years ago. As a result he became triggered by reflections- moving or otherwise – they would spark up an automatic reaction in him: barking, chasing, tremoring/shivering, whining and obsessively monitoring and following 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.
After a five-year buffer from being exposed to his triggers as much as possible, it is now 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. Management is still key and will be for the rest of his life. It isn’t fair for him to consistently be exposed to something that still causes a stress reaction in his body. We have to be extremely aware of potential difficulties- from using blinds in the Summer, to avoiding walking past houses that use certain Christmas lights in the Winter.
There are ways of helping your dog overcome this compulsive behaviour but as with everything, prevention is better than cure. To be happy and healthy, dogs have a myriad of natural behaviours that need to be expressed through play and activities (problem solving, digging, sniffing, scavenging, licking etc). This can be achieved with a variety of enrichment activities. It is not a natural behaviour for a dog to chase after a light, there is no good reason to ever resort to this. For the sake of your dogs physical and mental health – stay clear!