Who ever assured you that deer wouldn't eat Rugosas obviously knows nothing about deer. Deer don't like the many thorns and bristles on the canes but their favourite thing to eat is the new growth at the ends of the canes. If really hungry they will also eat any leaves that are on the outsides where their muzzle won't come into contact with the thorns. I live in deer country and most of the time they don't eat Rugosas lower down, but they do eat them. I find that Rabbits eat the foliage lower downand they also knaw on the lower canes too. When your Rugosas have made some old canes, they should be able to survive the onslot of the deer.