I was hoping the visit to UC Davis would provide a final answer regarding Popeye's legs but I guess I should have learned by now that it would only open more questions. 3 general vets and 1 neurologist have suggested that amputation would improve Popeye's mobility, yet the orthopedic surgeon at UCD recommended against it. Essentially, her reasons were:
1) Popeye moves around well enough as he is.
2) Generally when dogs have their hind legs amputated, it is done at the mid-thigh. Muscle in that area is then used to flap over the wound and provide protection of the bone. In Popeye's case however, he has no muscle there so the bone would be vulnerable were he to try to walk or drag on his stumps.
3) Should amputation be performed, the UCD vet said she would do it at the hips, and this would compromise his ability to move as well in a cart.
I called Eddie's Wheels and they confirmed that the couple of dogs they've built carts for who were amputated at the hips did not get around as well in their carts as the ones who still had their legs. They referred me to this video of a paralyzed cat for whom they built a cart. As the video shows, the cat's hind legs are similar to Popeye's and Eddie's Wheels attached straps to the cart to hold her legs tucked under her chest.
(By the way, the young man in the video above is amazing. If you have a chance to watch his other videos, you can do so at http://www.youtube.com/profile_videos?user=ngothyeaun.)
If the choice was only between not amputating Popeye's legs and amputating at the hips, I would choose not amputating. But different vets have given me different opinions about the possibility of amputating at the thighs, and I haven't completely ruled out that option yet.
The one thing that the vets do all agree with is that Popeye would do great in a cart, but that we should wait at least a couple more months until he is done growing before getting him one. I may decide to take him to another orthopedic specialist for another opinion in the future, but for now, we just wait for the day when we can get him his wheels.