>She ended up walking completely on her pasterns and looking like a sealion
I suspect Goldmali is talking about my girl. I had to have her put to sleep earlier this year at just under 9, no age at all for a collie but walking was just too painful in the end and in her head she was still a young active dog.
Gem's pasterns starting stretching and becoming weaker quite early on. unfortunately because the pasterns were not working the way they should (as shock absorbers) she also developed arthritis in her wrists. She was seen by a top orthopaedic surgeon but there wasn't anything he could do for her. I kept her going with a combination of herbal/homoeopathic remedies, conventional nsaids and physical supports. I used glucosamine and chondroitin, green lipped muscle and rhus tox and bought some leather wrist wraps that had plastic stiffeners in them. These worked quite well until her arthritis became so bad it was too sore to use them. She was also on metacam for many years, and latterly previcox and tramadol.
The vet thought that doing agility training in an indoor arena may have strained her pasterns, I thought jumping on the sand surface would be good but he said it is very hard work.
Gem is the dog on the left, her legs look very similar to your girls, hope the support works.