Yes Sable it was very scary. It happens so fast, one minute he was following me around as I was late that night coming home (him knowing the time) caused him to have some anxiety. So, when I arrived home, he pretty much followed me around the house. I sat down to eat, and he was right next to me, when we both went to get up, he couldn't get his rear legs up to even balance himself. If this happens to anyone elses sheltie, and I really hope it doesn't. Immediate attention is the best way for recovery. We didn't do the blood or x-rays as these test most likely would not show much, the vet started him right on medication, with a shot of pretizone, and an anti-biodic. It was a very good call to do. Today is two weeks and he really is like his normal self except his left rear leg doesn't have the strength it did. Today, he woke up and was lifting his rear up with his right rear leg and dragging the left rear leg. He will also stand up for about 4 mins with no help, little wobbly, but he does stand.
Ever since he came to us, he has been a inside sheltie. Not much for being outside, as I think the puppymill kept him outside. So, now he loves the comfort of being warm and being around us.