I buy them from Holland & Barret and gave 4 x 500mg a day for horse. Wasn't sure whether MAxavita or H&B were making any significant change so have taken him off everything! However, have been giving 1 x 250mg to the cat and she's gone from very slowing slipping of the window sill to jumping from it to the arm of my chair (with a massive landing thump!) I'd say they're certainly working for the moggie!!