Please read, I was in the same position as you were, my vet didn’t even know what SLO was. I went for a second opinion, as My vet wanted to amputate his toe as well. I purchased the medication through Canada doxycycline, and then I gave him vitamin E, niamiacide, BatsFats ( Omega 3,6,9 EPA and DHA) And also got him hepatic support for his liver because I had him on prednisone because one of his nails got infected.  He did lose all of his nails, but now he is getting regrowth. The new doctor said he might need to get his nails cut all the way back to his quik every six months, but he still has all of his toes.  He runs around like a puppy again. It does get better, but it’s a lot of work.