Here is a picture of Sadie (red collar) and Shelly (purple collar). Sadie is a Black Lab/Rhodesian Ridgeback and keeps up well running with Greyhounds at the dog park. She can switch directions at full speed 30MPH, in one stride. It is unbelievable to see. Shelly is a Saluki/Black Lab mix and will hunt incessantly in my yard. Both dogs were rescued from shelters.