[Atlantia]

My dog, Toby (a collie cross), is sixteen; though he acts very much a puppy most of the time.
For a little while though, he has shown signs of weakness in his back legs, it appears as though he can't stand up properly. Then other times, Toby races about the house and jumps about, as though there is nothing wrong with him. If anyone knows of any suplements which might help, I'd be grateful. Might have to end up taking Toby to the vets, but he's terrified of the place.