I consider my hounds seniors at 10, but it is pretty arbitrary! Fletcher has been getting supplements for a few years, because he started showing symptoms of arthritis when he was only 6. He just turned 10, and his arthritis is pretty bad, but in his mind, he is still only about 2 Molly will be 10 in May, and doesn't seem like a "senior" at all! I've been giving the girls Joint Health and Fresh Factors for a couple of years, figured it couldn't hurt, and might help put off the old age creaks for a bit.