Hello and welcome to Willow.
This is a sweet spaniel.
He ruptured his cruciate ligament.
He had a TPLO surgery. This is a very successful type of surgery. His recovery waa good, but as so often with these cases, he had extensive muscle loss.
So we set a program to encourage muscle to not deteriorate through the early phases of recovery, and then gradally grow the muscle bulk as he improves.
He is doing really well. Well done mum and Willow!