Help save Loki

My beautiful 1 year old dog, Loki, became unwell a couple of months ago. He became very lethargic with no appetite. The vet ran a series of blood tests, but they couldn’t find the answer. Loki was put on a drip, was given morphine, and came home that night. Loki seemed to get better for 2 weeks, but, once again became very ill. More blood tests revealed, that Loki had an autoimmune disease, this was causing his red blood cell count to drop dangerously low. Loki was put on a course of steroids, which made him ravenously hungry, but he seemed to be better. We noticed that Loki was losing weight and more alarmingly, muscle mass. But we persevered, Loki had to go to the vets, once a week, to check his red blood cell count. For awhile, all was good, but our vet said that steroids were destroying his body, so advised us to halve the dose. Loki wasn’t as hungry, and seemed more like himself. Monday morning, I found Loki just lying down. He couldn’t get up to say hello. My son and I took him straight to the vets. They took some blood, the count had gone down. The vet said that Loki would need to go onto a medication, called Atopica. I asked how much this medication would be, it is $1000 a month. As you can imagine, I just burst into tears. I love my dog so so much. The thought of having to say goodbye to him just breaks my heart. Loki was born on April fools day, so he is just over 1, he’s still a baby. I don’t know what to do. The vet said this may or may not work, but I have to try. Please help Loki.