I would teach her to jump on the ottoman seperately from the bed. Then when she can do that put it beside the bed and have her jump on it, then onto the bed. Also you will want to spend time teaching her to use it to get off the bed as well, since it is so high you don't want to stress her joints by her landing on them from such a distance.

Or like Kay said you can look into places that sell dog stairs specifically for that purpose... the same companies have ramps for dogs too I think.