One of my clients kindly filmed this video when she was at the beach with her dog.
It clearly shows gravity force in action. Our dogs body and limbs go through a lot during ball play. Here you can see how the paw prints change depth in the sand dramatically, when the ball is clearly caught. You then see the instant direction change too.
We are not saying to never have fun. But its always worth bearing this information in mind, especially if old or debilitated. Its worth also keeping it in mind when young, to help avoid excessive stress and strain that can lead to disease or injury.
Thank you for the video Kathryn. Its wonderful to share examples and see proof of these issues. We can learn so much from sand.