I recently bought a dog StreamZ Smart Collar from eVet to see if it would hep with my dogs stiff hind legs & back. I am very happy with the result! Alfie is my 13 year old Jack Russell, who a couple of years ago sustained an injury to his back. This was corrected with surgery, but has since been a bit slower and stiffer in his back & hind legs, more so in the past month. I was skeptical, but within 24 hours of warring the Smart Collar, he was able to jump up onto the sofa again and was running along with his tail in the air which he hasn't been able to do for a while. I would highly recommend this product to anyone with an older dog.