Don’t allow chase or wrestle games between a very large and a very small dog. If you see this happening, call your dog away with a treat. At the park, seek out areas with more dogs his own size.
Why is this important? Dogs love to chase things—balls, cats, sticks, Frisbees, and other dogs. They get this love from their wolf ancestry, along with the instincts to stalk, and grab and shake small prey animals. But wolves are all about the same size and live in the same social group their entire lives. Dogs, by contrast, have been bred into a staggering variety of sizes, and regularly meet dogs that are new to them. When dogs chase each other or wrestle, one dog may panic and begin to shriek or struggle like a prey animal. If that happens, a predatory reflex in the other dog may kick in.
Instincts are instincts.
Even dogs not usually into hunting-type activities can have their predatory reflexes triggered if the situation resembles a predator-prey interaction. A good example is when one dog flees from another in a good, old-fashioned game of chase. The rapidly retreating dog suddenly looks like prey.
The risk of predatory reflexes being triggered is much greater when there’s a big size difference between two dogs.
So, supervise your dog’s play sessions and be prepared to break up interactions with much larger or much smaller dogs. It’s safer for everyone.