Protein Powder?

My chin, Chloe was diagnosed with dental disease about 3+ months ago. She went in for her 3rd filing today. I've been trying really hard to get her to eat more hay to grind her teeth down and I do limit her pellets because she eats more hay that way. The vet said she has muscle wasting and needs a protein supplement. I'm guessing it's from the decrease in pellets as that's really her main source of protein. If that's the case then she may be deficient or in danger of being deficient in some other nutrients that she mainly gets from pellets. I will bump up her pellets (maybe mix in some mazuri or something), though I hope it doesn't decrease her hay consumption. Her weight is unchanged from the past year essentially.
My question is, does anyone have any experience with protein powder supplements? I don't know if I've heard of a chin on protein supplements. My gut says to just up her pellets and call it a day but obviously I am no expert and she is my first and only chin so I have no experience to compare it to.
Thanks!